drm/amd/display: Early return on crc get

If crc is disabled, early return when getting crc's. That way, we avoid
reading extra registers within the pflip high irq.

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h

@@ -212,6 +212,7 @@ struct dm_crtc_state {
 	struct dc_stream_state *stream;
 
 	bool crc_first_skipped;
+	bool crc_enabled;
 };
 
 #define to_dm_crtc_state(x)    container_of(x, struct dm_crtc_state, base)