There is a null check on pointer lpfc_cmd after the pointer has been
dereferenced when pointers rdata and ndlp are initialized at the start of
the function. Fix this by only assigning rdata and ndlp after the pointer
lpfc_cmd has been null checked.

Link: https://lore.kernel.org/r/20201118131345.460631-1-colin.king@canonical.com
Fixes: 96e209be ("scsi: lpfc: Convert SCSI I/O completions to SLI-3 and SLI-4 handlers")
Reviewed-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Addresses-Coverity: ("Dereference before null check")