drm/amd/display: set MSA MISC1 bit 6 when using VSC SDP for DCE 11.x

drm/amd/display: set MSA MISC1 bit 6 when using VSC SDP for DCE 11.x

When BT.2020 colorimetry is selected, the driver sends information using
VSC SDP but does not set "ignore MSA colorimetry" bit on older GPUs with
DCE-based IPs. This causes certain sinks to prefer colorimetry
information in DP MSA, resulting in terrible color rendering ("dull"
colors) when HDR is enabled.

This commit wires up the MISC1 bit 6 for GPUs with DCE 11.x based IPs to
correctly configure sinks to ignore colorimetry information in MSA,
resolving the color rendering issue.

Closes: https://gitlab.freedesktop.org/drm/amd/-/work_items/4849
Assisted-by: oh-my-pi:GPT-5.5
Signed-off-by: Leorize <leorize+oss@disroot.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 323a09e56c1d549ce47d4f110de77b0051b4a8bf)
Cc: stable@vger.kernel.org