drm/amdgpu/display: Drop some new CONFIG_DRM_AMD_DC_DCN1_01 guards

These got added back by subsequent merges accidently.

Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>