mfd: Add Ampere's Altra SMpro MFD driver

Adds Multi-function devices driver for SMpro co-processor found on the
Mt.Jade hardware reference platform with Ampere's Altra processor family.

Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20220929094321.770125-9-quan@os.amperecomputing.com