scsi: core: Use 32-bit hostnum in scsi_host_lookup()

Change scsi_host_lookup() hostnum argument type from unsigned short to
unsigned int to match the type used everywhere else.

Fixes: 6d49f63b

 ("[SCSI] Make host_no an unsigned int")
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Link: https://lore.kernel.org/r/a02497e7-c12b-ef15-47fc-3f0a0b00ffce@cybernetics.com
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>