drm/rockchip: dw_hdmi: Handle suspend/resume

On Rockchip rk3288-based Chromebooks when you do a suspend/resume
cycle:

1. You lose the ability to detect an HDMI device being plugged in.

2. If you're using the i2c bus built in to dw_hdmi then it stops
working.

Let's call the core dw-hdmi's suspend/resume functions to restore
things.

NOTE: in downstream Chrome OS (based on kernel 3.14) we used the
"late/early" versions of suspend/resume because we found that the VOP
was sometimes resuming before dw_hdmi and then calling into us before
we were fully resumed.  For now I have gone back to the normal
suspend/resume because I can't reproduce the problems.

Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190604204207.168085-2-dianders@chromium.org