scsi: lpfc: sanity check hrq is null before dereferencing it

From: Colin Ian King <colin.king@canonical.com>

The sanity check for hrq should be moved to before the deference
of hrq to ensure we don't perform a null pointer deference.

Detected by CoverityScan, CID#1411650 ("Dereference before null check")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: James Smart <james.smart@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>