video: rockchip: hdmi: improve hdr function when out of sink tmds clk

video: rockchip: hdmi: improve hdr function when out of sink tmds clk

If output tmdsclk is out of sink max tmds clk, we need to set output
mode to 8bit or YCbCr422.

For example, sink max tmds clk is 600M, but 3840x2160p-60 10bit tmdsclk
is 594*1.25 > 600, we set output mode to YCbCr422 10bit which tmds clk
is 594, so we can get max picture quality.

Change-Id: I13fe30dad06757ec52de8d367f1e10a56e63ad92
Signed-off-by: Zheng Yang <zhengyang@rock-chips.com>
(cherry picked from commit 0c3397a9b8b4da4ca3a67e5a6d88abf20f00f184)