ANDROID: GKI: Enable POWER_RESET_SYSCON

Enable support for board reset with "generic" syscon register mappings.

This feature is needed by CONFIG_SYSCON_REBOOT_MODE which some boards
may build as a module to communicate the reboot mode back to the
bootloader.

This feature is used by rockchip platforms such as Rock Pi 4.

Bug: 183962924
Change-Id: Icfdebf29777533799e238fdadf1de064f271c856
Signed-off-by: Alistair Delva <adelva@google.com>