Variable 'tag' is currently an unsigned int and is being compared to less
than zero, this check is always false. Fix this by making 'tag' an int.

Link: https://lore.kernel.org/r/20210806144301.19864-1-colin.king@canonical.com
Fixes: 4728ab4a ("scsi: ufs: Remove ufshcd_valid_tag()")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Addresses-Coverity: ("Macro compares unsigned to 0")