Fixes the following W=1 kernel build warning(s):

 In file included from drivers/gpu/drm/amd/amdgpu/../display/dc/dce112/dce112_resource.c:59:
 drivers/gpu/drm/amd/amdgpu/../include/asic_reg/dce/dce_11_2_sh_mask.h:10480:62: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:96:16: note: in expansion of macro ‘FMT_BIT_DEPTH_CONTROL__FMT_TEMPORAL_DITHER_EN__SHIFT’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:114:2: note: in expansion of macro ‘OPP_SF’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:148:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_COMMON_BASE’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce112/dce112_resource.c:321:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_112’
 drivers/gpu/drm/amd/amdgpu/../include/asic_reg/dce/dce_11_2_sh_mask.h:10480:62: note: (near initialization for ‘opp_shift.FMT_TEMPORAL_DITHER_EN’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:96:16: note: in expansion of macro ‘FMT_BIT_DEPTH_CONTROL__FMT_TEMPORAL_DITHER_EN__SHIFT’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:114:2: note: in expansion of macro ‘OPP_SF’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:148:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_COMMON_BASE’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce112/dce112_resource.c:321:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_112’
 drivers/gpu/drm/amd/amdgpu/../include/asic_reg/dce/dce_11_2_sh_mask.h:10479:60: warning: initialized field overwritten [-Woverride-init]
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:96:16: note: in expansion of macro ‘FMT_BIT_DEPTH_CONTROL__FMT_TEMPORAL_DITHER_EN_MASK’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:114:2: note: in expansion of macro ‘OPP_SF’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:148:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_COMMON_BASE’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce112/dce112_resource.c:325:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_112’
 drivers/gpu/drm/amd/amdgpu/../include/asic_reg/dce/dce_11_2_sh_mask.h:10479:60: note: (near initialization for ‘opp_mask.FMT_TEMPORAL_DITHER_EN’)
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:96:16: note: in expansion of macro ‘FMT_BIT_DEPTH_CONTROL__FMT_TEMPORAL_DITHER_EN_MASK’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:114:2: note: in expansion of macro ‘OPP_SF’
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_opp.h:148:2: note: in expansion of macro ‘OPP_COMMON_MASK_SH_LIST_DCE_COMMON_BASE’

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Mauro Rossi <issor.oruam@gmail.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>