drm/bridge: anx7625: Set downstream sink into normal status

As downstream sink was set into standby mode while bridge disabled,
this patch used for setting downstream sink into normal status
while enable bridge.

Signed-off-by: Xin Ji <xji@analogixsemi.com>
Reviewed-by: Pin-Yen Lin <treapking@chromium.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220322080213.1487134-1-xji@analogixsemi.com