Revert "drm/amd/display: Hardware cursor changes color when switched to software...

Revert "drm/amd/display: Hardware cursor changes color when switched to software cursor"

This reverts commit 272e6aab14bbf98d7a06b2b1cd6308a02d4a10a1.

Applying degamma curve to the cursor by default breaks Linux userspace
expectation.

On Linux, AMD display manager enables cursor degamma ROM just for
implict sRGB on HW versions where degamma is split into two blocks:
degamma ROM for pre-defined TFs and `gamma correction` for user/custom
curves, and degamma ROM settings doesn't apply to cursor plane.

Link: https://gitlab.freedesktop.org/drm/amd/-/issues/1513
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2803
Reported-by: Michel Dänzer <michel.daenzer@mailbox.org>
Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/4144
Signed-off-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>