scsi: fnic: Code cleanup

scsi: fnic: Code cleanup

Replace existing host structure with fnic host.

Add headers from scsi to support new functionality.

Remove unused code and declarations.

Reviewed-by: Sesidhar Baddela <sebaddel@cisco.com>
Reviewed-by: Arulprabhu Ponnusamy <arulponn@cisco.com>
Reviewed-by: Gian Carlo Boffa <gcboffa@cisco.com>
Signed-off-by: Karan Tilak Kumar <kartilak@cisco.com>
Link: https://lore.kernel.org/r/20241212020312.4786-14-kartilak@cisco.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>