power: reset: Add msm restart support

Add support for restart and poweroff functionality present on MSM chipsets
with the MPM2 ps-hold hardware.

Signed-off-by: Abhimanyu Kapur <abhimany@codeaurora.org>
Tested-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Anton Vorontsov <anton@enomsg.org>