drm/msm/dp: return correct Colorimetry for DP_TEST_DYNAMIC_RANGE_CEA case

MSA MISC0 bit 1 to 7 contains Colorimetry Indicator Field.
dp_link_get_colorimetry_config() returns wrong colorimetry value
in the DP_TEST_DYNAMIC_RANGE_CEA case in the current implementation.
Hence fix this problem by having dp_link_get_colorimetry_config()
return defined CEA RGB colorimetry value in the case of
DP_TEST_DYNAMIC_RANGE_CEA.

Changes in V2:
-- drop retrieving colorimetry from colorspace
-- drop dr = link->dp_link.test_video.test_dyn_range assignment

Changes in V3:
-- move defined MISCr0a Colorimetry vale to dp_reg.h
-- rewording commit title
-- rewording commit text to more precise describe this patch

Fixes: c943b494

 ("drm/msm/dp: add displayPort driver support")
Signed-off-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/574888/
Link: https://lore.kernel.org/r/1705526010-597-1-git-send-email-quic_khsieh@quicinc.com
Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>