refator(mediatek): move pmic.[c|h] to common folder

These two files are identical on MT8192 and MT8195. They can also be
used on MT8188. So move them to common/drivers/pmic/.

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: I8c12d15f1da79ab5767ac02b3ab70e8508155ee8