The HDMI controller in the A31 SoC is slightly different from the
earlier version. In addition to the TMDS clock and DDC controls,
this version now takes a second DDC clock input.

Add a compatible string for it, and add the DDC clock input to the
list of clocks required.
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010032008.682-7-wens@csie.org