MAX8907 PMIC has embedded poweroff function used by some device to initiane
device power off. Implement it as optional sysreset driver guarded by
kconfig option and system-power-controller device tree property.
Tested-by: Ion Agorria <ion@agorria.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
