scsi: ufs: Add UFS platform driver for Cadence UFS

This patch adds a device tree platform driver for Cadence UFS Host
Controller.  It can be enabled with SCSI_UFS_CDNS_PLATFORM Kconfig option.

Signed-off-by: Jan Kotas <jank@cadence.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>