soc: mediatek: mt8167-mmsys: Fix missing regval in all entries

The mmsys routing table for this SoC was effectively missing
initialization of the val variable of struct mtk_mmsys_routes:
this means that `val` was incorrectly initialized to zero,
hence the registers were wrongly initialized.

Add the required regval to all of the entries of the routing
table for this SoC to fix display controller functionality.

Fixes: 060f7875 ("soc: mediatek: mmsys: Add support for MT8167 SoC")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>