clk: mediatek: mt7622: add missing clock PERI_UART4_PD

Add missing clock PERI_UART4_PD for peri clock gates. This is needed to
match upstream linux clk ID in preparation for OF_UPSTREAM.
Also convert infracfg to mux + gate implementation as now we have mux on
top of gates.

Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
2 files changed