scsi: lpfc: Use unsigned type for num_sge

LUNs going into "failed ready running" state observed on >1T and on even
numbers of size (2T, 4T, 6T, 8T and 10T). The issue occurs when DIF is
enabled at the host.

The kernel logs:

  Cannot setup S/G List for HBAIO segs 1/1 SGL 512 SCSI 256: 3 0

The host lpfc driver is failing to setup scatter/gather list (protection
data) for the I/Os.

The return type lpfc_bg_setup_sgl()/lpfc_bg_setup_sgl_prot() causes the
compiler to remove the most significant bit. Use an unsigned type instead.

Signed-off-by: Hannes Reinecke <hare@suse.de>
[dwagner: added commit message]
Signed-off-by: Daniel Wagner <dwagner@suse.de>
Link: https://lore.kernel.org/r/20231220162658.12392-1-dwagner@suse.de
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>