drm/radeon: implement output csc property for DCE5+

[Dan Carpenter]

Hello Alex Deucher,

This is a semi-automatic email about new static checker warnings.

The patch 643b1f5629a3: "drm/radeon: implement output csc property 
for DCE5+" from Feb 23, 2015, leads to the following Smatch complaint:

drivers/gpu/drm/radeon/radeon_connectors.c:763 radeon_connector_set_property()
         error: we previously assumed 'connector->encoder' could be null (see 
line 751)

drivers/gpu/drm/radeon/radeon_connectors.c
   750          if (property == rdev->mode_info.output_csc_property) {
   751                  if (connector->encoder)
                            ^^^^^^^^^^^^^^^^^^
Check.

   752                          radeon_encoder = 
to_radeon_encoder(connector->encoder);
   753                  else {
   754                          struct drm_connector_helper_funcs 
*connector_funcs = connector->helper_private;
   755                          radeon_encoder = 
to_radeon_encoder(connector_funcs->best_encoder(connector));
   756                  }
   757  
   758                  if (radeon_encoder->output_csc == val)
   759                          return 0;
   760  
   761                  radeon_encoder->output_csc = val;
   762  
   763                  if (connector->encoder->crtc) {
                            ^^^^^^^^^^^^^^^^^^
Unchecked dereference.

   764                          struct drm_crtc *crtc  = 
connector->encoder->crtc;
   765                          struct drm_crtc_helper_funcs *crtc_funcs = 
crtc->helper_private;

regards,
dan carpenter