mfd: mt6397: Add MT6358 register definitions for power key

To support power/home key detection, add definitions for
two more MT6358 PMIC registers:

- TOPSTATUS: homekey and powerkey debounce status
- TOP_RST_MISC: controls homekey,powerkey long press reset time

Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>