drm/amd/display: Don't set DSC for phantom pipes

[Description]
Don't set DSC bit for phantom pipes, not
required since phantom pipe don't have
any actual output
Reviewed-by: NJun Lei <Jun.Lei@amd.com>
Acked-by: NBrian Chang <Brian.Chang@amd.com>
Signed-off-by: NAlvin Lee <Alvin.Lee2@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dml/dcn32/dcn32_fpu.c

@@ -493,6 +493,7 @@ void dcn32_set_phantom_stream_timing(struct dc *dc,
 						phantom_stream->timing.v_front_porch +
 						phantom_stream->timing.v_sync_width +
 						phantom_bp;
+	phantom_stream->timing.flags.DSC = 0; // Don't need DSC for phantom timing
 }
 
 /**