scsi: fc: remove redundant check of an unsigned long being less than zero

The check for an unsigned long being less than zero is always false so
it is a redundant check and can be removed.

Detected by static analysis with by PVS-Studio

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>