scsi: ibmvfc: Fix NULL return compiler warning

Fix up a compiler warning introduced via 54b04c99d02e

Link: https://lore.kernel.org/r/1583159961-15903-1-git-send-email-brking@linux.vnet.ibm.com


Fixes: 54b04c99d02e ("scsi: ibmvfc: Avoid loss of all paths during SVC node reboot")
Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>