drm/amd/display: remove duplicate format modifier

drm/amd/display: remove duplicate format modifier

amdgpu_dm_plane_get_plane_modifiers always adds DRM_FORMAT_MOD_LINEAR to
the list of modifiers. However, with gfx12,
amdgpu_dm_plane_add_gfx12_modifiers also adds that modifier to the list.
So we end up with two copies. Most apps just ignore this but some
(Weston) don't like it.

As a fix, we change amdgpu_dm_plane_add_gfx12_modifiers to not add
DRM_FORMAT_MOD_LINEAR to the list, matching the behavior of analogous
functions for other chips.

Signed-off-by: Erik Kurzinger <ekurzinger@gmail.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>