scsi: fnic: Add and use fnic number

scsi: fnic: Add and use fnic number

Add fnic_num in fnic.h to identify fnic in a multi-fnic environment.
Increment and set the fnic number during driver load in fnic_probe.
Replace the host number with fnic number in debugfs.

Reviewed-by: Sesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: Arulprabhu Ponnusamy <arulponn@cisco.com>
Signed-off-by: Karan Tilak Kumar <kartilak@cisco.com>
Link: https://lore.kernel.org/r/20231211173617.932990-3-kartilak@cisco.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>