arm64: dts: mt7622: update a clock property for UART0

The input clock of UART0 should be CLK_PERI_UART0_PD.

Fixes: 13f36c32 ("arm64: dts: mt7622: turn uart0 clock to real ones")
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>