scsi: sd: define variable dif as unsigned int instead of bool

Variable dif in function sd_setup_read_write_cmnd() is the return value of
function scsi_host_dif_capable() which returns dif capability of disks.  If
define it as bool, even for the disks which support DIF3, the function
still return dif=1, which causes IO error. So define variable dif as
unsigned int instead of bool.

Fixes: e249e42d

 ("scsi: sd: Clean up sd_setup_read_write_cmnd()")
Link: https://lore.kernel.org/r/1571725628-132736-1-git-send-email-chenxiang66@hisilicon.com
Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>