scsi: ufs: Add SPDX GPL-2.0 to replace GPL v2 boilerplate

Add SPDX GPL-2.0 to UFS driver files that specified the GPL version 2
license, remove the full boilerplate text.

Link: https://lore.kernel.org/r/20200605200520.20831-2-huobean@gmail.com


Reviewed-by: Tomas Winkler <tomas.winkler@intel.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>