soc: mediatek: pwrap: add support for MT7622 SoC

Add the registers, callbacks and data structures required to make the
PMIC wrapper work on MT7622.

Signed-off-by: Chenglin Xu <chenglin.xu@mediatek.com>
Signed-off-by: Chen Zhong <chen.zhong@mediatek.com>
Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>