Preserve the destination mode's list head in drm_mode_copy. Just
in case someone decides that it's a good idea to overwrite a mode which
happens to be on some list,
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NAlex Deucher <alexander.deucher@amd.com>
Signed-off-by: NDave Airlie <airlied@redhat.com>