scsi: ufs: Add program_key() variant op

scsi: ufs: Add program_key() variant op

On Snapdragon SoCs, the Linux kernel isn't permitted to directly access the
standard UFS crypto configuration registers.  Instead, programming and
evicting keys must be done through vendor-specific SMC calls.

To support this hardware, add a ->program_key() method to 'struct
ufs_hba_variant_ops'.  This allows overriding the UFS standard key
programming / eviction procedure.

Link: https://lore.kernel.org/r/20200710072013.177481-5-ebiggers@kernel.org
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>