dt-bindings: mfd: Add bindings for Ampere Altra SMPro MFD driver

Adds device tree bindings for SMPro MFD driver found on the Mt.Jade
hardware reference platform with Ampere's Altra Processor family.

The SMpro co-processor on Ampere Altra processor family is to monitor
and report various data included hwmon-related info, RAS errors, and
other miscellaneous information.

Signed-off-by: Quan Nguyen <quan@os.amperecomputing.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20221031024442.2490881-2-quan@os.amperecomputing.com