scsi: lpfc: Fix list_entry null check warning in lpfc_cmpl_els_plogi()

scsi: lpfc: Fix list_entry null check warning in lpfc_cmpl_els_plogi()

Smatch called out a warning for null checking a ptr that is assigned by
list_entry(). list_entry() does not return null and, if the list is empty,
can return an invalid ptr. Thus, the !psrp check does not execute properly.

 drivers/scsi/lpfc/lpfc_els.c:2133 lpfc_cmpl_els_plogi()
 warn: list_entry() does not return NULL 'prsp'

Replace list_entry() with list_get_first(), which does a list_empty() check
before returning the first entry.

Fixes: a3c3c0a806f1 ("scsi: lpfc: Validate ELS LS_ACC completion payload")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-scsi/01b7568f-4ab4-4d56-bfa6-9ecc5fc261fe@moroto.mountain/
Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20231031191224.150862-4-justintee8345@gmail.com
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>