scsi: ufs: Change upiu_flags to be u8

According to the UFS Spec, the Flags field in the UPIU is one byte in size,
not 4. Change it to be u8.

Link: https://lore.kernel.org/r/20200706123936.24799-1-huobean@gmail.com


Tested-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>