arm: dts: mt6323: add keys, power-controller, rtc and codec

support poweroff and power-related keys on bpi-r2

Suggested-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Josef Friedl <josef.friedl@speed.at>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>