mfd: mt6397: Modify suspend/resume behavior

Some pmics don't need backup interrupt settings, so we change to use
pm notifier for the pmics which are necessary to store settings.

Signed-off-by: Hsin-Hsiung Wang <hsin-hsiung.wang@mediatek.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
3 files changed