ice: fix overwriting TX/RX descriptor values when rebuilding VSI

If a user sets the value of the TX or RX descriptors to some non-default
value using 'ethtool -G' then we need to not overwrite the values when
we rebuild the VSI. The VSI rebuild could happen as a result of a user
setting the number of queues via the 'ethtool -L' command. Fix this by
checking to see if the value we have stored is non-zero and if it is
then don't change the value.
Signed-off-by: Paul M Stillwell Jr <paul.m.stillwell.jr@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_lib.c

@@ -127,8 +127,14 @@ static void ice_vsi_set_num_desc(struct ice_vsi *vsi)
 	case ICE_VSI_PF:
 	case ICE_VSI_CTRL:
 	case ICE_VSI_LB:
-		vsi->num_rx_desc = ICE_DFLT_NUM_RX_DESC;
-		vsi->num_tx_desc = ICE_DFLT_NUM_TX_DESC;
+		/* a user could change the values of num_[tr]x_desc using
+		 * ethtool -G so we should keep those values instead of
+		 * overwriting them with the defaults.
+		 */
+		if (!vsi->num_rx_desc)
+			vsi->num_rx_desc = ICE_DFLT_NUM_RX_DESC;
+		if (!vsi->num_tx_desc)
+			vsi->num_tx_desc = ICE_DFLT_NUM_TX_DESC;
 		break;
 	default:
 		dev_dbg(ice_pf_to_dev(vsi->back), "Not setting number of Tx/Rx descriptors for VSI type %d\n",