net/ncsi: Simplify Kconfig/dts control flow

Background:

1. CONFIG_NCSI_OEM_CMD_KEEP_PHY

If this is enabled, we send an extra OEM Intel command in the probe
sequence immediately after discovering a channel (e.g. after "Clear
Initial State").

2. CONFIG_NCSI_OEM_CMD_GET_MAC

If this is enabled, we send one of 3 OEM "Get MAC Address" commands from
Broadcom, Mellanox (Nvidida), and Intel in the *configuration* sequence
for a channel.

3. mellanox,multi-host (or mlx,multi-host)

Introduced by this patch:

https://lore.kernel.org/all/20200108234341.2590674-1-vijaykhemka@fb.com/

Which was actually originally from cosmo.chou@quantatw.com:

https://github.com/facebook/openbmc-linux/commit/9f132a10ec48db84613519258cd8a317fb9c8f1b

Cosmo claimed that the Nvidia ConnectX-4 and ConnectX-6 NIC's don't
respond to Get Version ID, et. al in the probe sequence unless you send
the Set MC Affinity command first.

Problem Statement:

We've been using a combination of #ifdef code blocks and IS_ENABLED()
conditions to conditionally send these OEM commands.

It makes adding any new code around these commands hard to understand.

Solution:

In this patch, I just want to remove the conditionally compiled blocks
of code, and always use IS_ENABLED(...) to do dynamic control flow.

I don't think the small amount of code this adds to non-users of the OEM
Kconfigs is a big deal.
Signed-off-by: Peter Delevoryas <peter@pjd.dev>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ncsi/ncsi-manage.c

@@ -689,8 +689,6 @@ static int set_one_vid(struct ncsi_dev_priv *ndp, struct ncsi_channel *nc,
 	return 0;
 }
 
-#if IS_ENABLED(CONFIG_NCSI_OEM_CMD_KEEP_PHY)
-
 static int ncsi_oem_keep_phy_intel(struct ncsi_cmd_arg *nca)
 {
 	unsigned char data[NCSI_OEM_INTEL_CMD_KEEP_PHY_LEN];
@@ -716,10 +714,6 @@ static int ncsi_oem_keep_phy_intel(struct ncsi_cmd_arg *nca)
 	return ret;
 }
 
-#endif
-
-#if IS_ENABLED(CONFIG_NCSI_OEM_CMD_GET_MAC)
-
 /* NCSI OEM Command APIs */
 static int ncsi_oem_gma_handler_bcm(struct ncsi_cmd_arg *nca)
 {
@@ -856,8 +850,6 @@ static int ncsi_gma_handler(struct ncsi_cmd_arg *nca, unsigned int mf_id)
 	return nch->handler(nca);
 }
 
-#endif /* CONFIG_NCSI_OEM_CMD_GET_MAC */
-
 /* Determine if a given channel from the channel_queue should be used for Tx */
 static bool ncsi_channel_is_tx(struct ncsi_dev_priv *ndp,
 			       struct ncsi_channel *nc)
@@ -1039,20 +1031,18 @@ static void ncsi_configure_channel(struct ncsi_dev_priv *ndp)
 			goto error;
 		}
 
-		nd->state = ncsi_dev_state_config_oem_gma;
+		nd->state = IS_ENABLED(CONFIG_NCSI_OEM_CMD_GET_MAC)
+			  ? ncsi_dev_state_config_oem_gma
+			  : ncsi_dev_state_config_clear_vids;
 		break;
 	case ncsi_dev_state_config_oem_gma:
 		nd->state = ncsi_dev_state_config_clear_vids;
-		ret = -1;
 
-#if IS_ENABLED(CONFIG_NCSI_OEM_CMD_GET_MAC)
 		nca.type = NCSI_PKT_CMD_OEM;
 		nca.package = np->id;
 		nca.channel = nc->id;
 		ndp->pending_req_num = 1;
 		ret = ncsi_gma_handler(&nca, nc->version.mf_id);
-#endif /* CONFIG_NCSI_OEM_CMD_GET_MAC */
-
 		if (ret < 0)
 			schedule_work(&ndp->work);
 
@@ -1404,7 +1394,6 @@ static void ncsi_probe_channel(struct ncsi_dev_priv *ndp)
 
 		schedule_work(&ndp->work);
 		break;
-#if IS_ENABLED(CONFIG_NCSI_OEM_CMD_GET_MAC)
 	case ncsi_dev_state_probe_mlx_gma:
 		ndp->pending_req_num = 1;
 
@@ -1429,7 +1418,6 @@ static void ncsi_probe_channel(struct ncsi_dev_priv *ndp)
 
 		nd->state = ncsi_dev_state_probe_cis;
 		break;
-#endif /* CONFIG_NCSI_OEM_CMD_GET_MAC */
 	case ncsi_dev_state_probe_cis:
 		ndp->pending_req_num = NCSI_RESERVED_CHANNEL;
 
@@ -1447,7 +1435,6 @@ static void ncsi_probe_channel(struct ncsi_dev_priv *ndp)
 		if (IS_ENABLED(CONFIG_NCSI_OEM_CMD_KEEP_PHY))
 			nd->state = ncsi_dev_state_probe_keep_phy;
 		break;
-#if IS_ENABLED(CONFIG_NCSI_OEM_CMD_KEEP_PHY)
 	case ncsi_dev_state_probe_keep_phy:
 		ndp->pending_req_num = 1;
 
@@ -1460,7 +1447,6 @@ static void ncsi_probe_channel(struct ncsi_dev_priv *ndp)
 
 		nd->state = ncsi_dev_state_probe_gvi;
 		break;
-#endif /* CONFIG_NCSI_OEM_CMD_KEEP_PHY */
 	case ncsi_dev_state_probe_gvi:
 	case ncsi_dev_state_probe_gc:
 	case ncsi_dev_state_probe_gls: