drm/bridge: anx7625: Add wait_hpd_asserted() callback

Move hpd polling check into wait_hpd_asserted() callback. For the cases
that aux transfer function wasn't used, do hpd polling check after pm
runtime resume, which will power on the bridge.

Signed-off-by: Hsin-Yi Wang <hsinyi@chromium.org>
Reviewed-by: Xin Ji <xji@analogixsemi.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220706125254.2474095-5-hsinyi@chromium.org