drm/amd/display: Clean some DCN32 macros

Some unused macros might mislead developers during the debug, which can
be removed without any issue. This commit drops some unused references
to SE_COMMON_MASK_SH_LIST_DCN32.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>