cnic: Refactor code and mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, refactor code a
bit and mark switch cases where we are expecting to fall through.

This patch fixes the following warning:

drivers/net/ethernet/broadcom/cnic.c: In function ‘cnic_cm_process_kcqe’:
drivers/net/ethernet/broadcom/cnic.c:4044:11: warning: this statement may fall through [-Wimplicit-fallthrough=]
    opcode = L4_KCQE_OPCODE_VALUE_CLOSE_COMP;
drivers/net/ethernet/broadcom/cnic.c:4050:2: note: here
  case L4_KCQE_OPCODE_VALUE_RESET_RECEIVED:
  ^~~~

Warning level 3 was used: -Wimplicit-fallthrough=3

Notice that, in this particular case, the code comment is modified
in accordance with what GCC is expecting to find.

This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/cnic.c

@@ -4038,15 +4038,14 @@ static void cnic_cm_process_kcqe(struct cnic_dev *dev, struct kcqe *kcqe)
 	case L5CM_RAMROD_CMD_ID_CLOSE: {
 		struct iscsi_kcqe *l5kcqe = (struct iscsi_kcqe *) kcqe;
 
-		if (l4kcqe->status != 0 || l5kcqe->completion_status != 0) {
+		if (l4kcqe->status == 0 && l5kcqe->completion_status == 0)
+			break;
+
 		netdev_warn(dev->netdev, "RAMROD CLOSE compl with status 0x%x completion status 0x%x\n",
 			    l4kcqe->status, l5kcqe->completion_status);
 		opcode = L4_KCQE_OPCODE_VALUE_CLOSE_COMP;
-			/* Fall through */
-		} else {
-			break;
-		}
 	}
+		/* Fall through */
 	case L4_KCQE_OPCODE_VALUE_RESET_RECEIVED:
 	case L4_KCQE_OPCODE_VALUE_CLOSE_COMP:
 	case L4_KCQE_OPCODE_VALUE_RESET_COMP: