drm/amd/display: change several dcn20 variables storage-class-specifier to static

smatch reports these similar problems in dcn20
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn20/dcn20_dsc.c:53:24:
  warning: symbol 'dcn20_dsc_funcs' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn20/dcn20_dwb.c:304:25:
  warning: symbol 'dcn20_dwbc_funcs' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn20/dcn20_mmhubbub.c:300:28:
  warning: symbol 'dcn20_mmhubbub_funcs' was not declared. Should it be static?
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn20/dcn20_mpc.c:545:24:
  warning: symbol 'dcn20_mpc_funcs' was not declared. Should it be static?

All of these are only used in their definition file, so they should be static
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dsc.c

@@ -50,7 +50,7 @@ static void dsc2_enable(struct display_stream_compressor *dsc, int opp_pipe);
 static void dsc2_disable(struct display_stream_compressor *dsc);
 static void dsc2_disconnect(struct display_stream_compressor *dsc);
 
-const struct dsc_funcs dcn20_dsc_funcs = {
+static const struct dsc_funcs dcn20_dsc_funcs = {
 	.dsc_get_enc_caps = dsc2_get_enc_caps,
 	.dsc_read_state = dsc2_read_state,
 	.dsc_validate_stream = dsc2_validate_stream,

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_dwb.c

@@ -301,7 +301,7 @@ void dwb2_set_scaler(struct dwbc *dwbc, struct dc_dwb_params *params)
 
 }
 
-const struct dwbc_funcs dcn20_dwbc_funcs = {
+static const struct dwbc_funcs dcn20_dwbc_funcs = {
 	.get_caps		= dwb2_get_caps,
 	.enable			= dwb2_enable,
 	.disable		= dwb2_disable,

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mmhubbub.c

@@ -297,7 +297,7 @@ void mcifwb2_dump_frame(struct mcif_wb *mcif_wb,
 	dump_info->size		= dest_height * (mcif_params->luma_pitch + mcif_params->chroma_pitch);
 }
 
-const struct mcif_wb_funcs dcn20_mmhubbub_funcs = {
+static const struct mcif_wb_funcs dcn20_mmhubbub_funcs = {
 	.enable_mcif		= mmhubbub2_enable_mcif,
 	.disable_mcif		= mmhubbub2_disable_mcif,
 	.config_mcif_buf	= mmhubbub2_config_mcif_buf,

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_mpc.c

@@ -542,7 +542,7 @@ static struct mpcc *mpc2_get_mpcc_for_dpp(struct mpc_tree *tree, int dpp_id)
 	return NULL;
 }
 
-const struct mpc_funcs dcn20_mpc_funcs = {
+static const struct mpc_funcs dcn20_mpc_funcs = {
 	.read_mpcc_state = mpc1_read_mpcc_state,
 	.insert_plane = mpc1_insert_plane,
 	.remove_mpcc = mpc1_remove_mpcc,