drm/meson: add support for HDMI2.0 2160p modes

Now we support the TMDS Clock > 3.4GHz and support the SCDC Control
operation in the DW-HDMI Controller, we can enable support for the
HDMI2.0 3840x2160@60/50 RGB444 display modes.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1549022873-40549-4-git-send-email-narmstrong@baylibre.com