drm/amd/display: Calculate output_color_space after pixel encoding adjustment

stable inclusion
from stable-v5.10.165
commit 75105d943d7a9de70856eb729c39ee73b3e541ec
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7T7G4

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=75105d943d7a9de70856eb729c39ee73b3e541ec



--------------------------------

commit 79601b89 upstream.

Code in get_output_color_space depends on knowing the pixel encoding to
determine whether to pick between eg. COLOR_SPACE_SRGB or
COLOR_SPACE_YCBCR709 for transparent RGB -> YCbCr 4:4:4 in the driver.

v2: Fixed patch being accidentally based on a personal feature branch, oops!

Fixes: ea117312 ("drm/amd/display: Reduce HDMI pixel encoding if max clock is exceeded")
Reviewed-by: Melissa Wen <mwen@igalia.com>
Signed-off-by: Joshua Ashton <joshua@froggi.es>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>