refator(mediatek): move drivers folder in common to plat/mediatek

We plan to put some soc related drivers in common/drivers. To reduce
confision, we move them to plat/mediatek.

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: I6b344e660f40a23b15151aab073d3045b28f52aa
22 files changed