RK3588/RK3576 hdmi color format setting and dsc mode setting are
the same mask in the same register. If dsc is enabled for hdmi in
uboot, what color is hdmi output in uboot that cannot be obtained
from this register in kernel.
Since hdmi in dsc mode always sends avi infoframe, color format
of hdmi output in uboot can be read from the avi register.
Change-Id: I68157455342302338370feb9176b46e2051b4f01
Signed-off-by: Algea Cao <algea.cao@rock-chips.com>