soc/mediatek/mt8192: Add mtcmos init support

Using common mtcmos code to power on audio and display modules in SOC.

TEST=Boots correctly on MT8192EVB. Passes the status check at the end of
     mtcmos_power_on()

Signed-off-by: Weiyi Lu <weiyi.lu@mediatek.com>
Change-Id: Ie7bff831eecfc2b4d315a577f6ff86befc483eab
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45394
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/mediatek/common/include/soc/mtcmos.h

@@ -6,6 +6,7 @@
 void mtcmos_audio_power_on(void);
 void mtcmos_display_power_on(void);
 
+void mtcmos_protect_audio_bus(void);
 void mtcmos_protect_display_bus(void);
 
 #endif /* __SOC_MEDIATEK_COMMON_MTCMOS_H__ */