drm/amdgpu/display: fix build when CONFIG_DRM_AMD_DC_DSC_SUPPORT=n

Add proper config check.
Reviewed-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dcn20/dcn20_resource.c

@@ -1922,8 +1922,10 @@ int dcn20_populate_dml_pipes_from_context(
 			pipes[pipe_cnt].dout.output_bpp = output_bpc * 3;
 		}
 
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
 		if (res_ctx->pipe_ctx[i].stream->timing.flags.DSC)
 			pipes[pipe_cnt].dout.output_bpp = res_ctx->pipe_ctx[i].stream->timing.dsc_cfg.bits_per_pixel / 16.0;
+#endif
 
 		/* todo: default max for now, until there is logic reflecting this in dc*/
 		pipes[pipe_cnt].dout.output_bpc = 12;