Merge branch 'drm-fixes-4.6' of git://people.freedesktop.org/~agd5f/linux into drm-fixes

two fixes for hw lockups and one for a double free

* 'drm-fixes-4.6' of git://people.freedesktop.org/~agd5f/linux:
  drm/amdgpu: make sure vertical front porch is at least 1
  drm/radeon: make sure vertical front porch is at least 1
  drm/amdgpu: set metadata pointer to NULL after freeing.