soc: mediatek: mmsys: add mt8186 mmsys routing table

Add new routing table for MT8186.
In MT8186, there are two routing pipelines for internal and external
display.

Internal display: OVL0->RDMA0->COLOR0->CCORR0->AAL0->GAMMA->POSTMASK0->
		  DITHER->DSI0
External display: OVL_2L0->RDMA1->DPI0

Signed-off-by: Yongqiang Niu <yongqiang.niu@mediatek.com>
Signed-off-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>