scsi_id: compiler warning on 32-bit

scsi_id: compiler warning on 32-bit

The sg_io_v4 interface passes pointers as u64s.  It turns out GCC
disapproves of us casting a u64 straight to a 32 bit pointer.

cc1: warnings being treated as errors
scsi_serial.c: In function ‘sg_err_category4’:
scsi_serial.c:159: warning: cast to pointer from integer of different size
scsi_serial.c: In function ‘scsi_dump_v4’:
scsi_serial.c:303: warning: cast to pointer from integer of different size