two radeon fixes
one MST fix,
one query addition, destined for stable, and to fix a regression
* 'drm-fixes-4.1' of git://people.freedesktop.org/~deathsimple/linux:
drm/radeon: don't probe MST on hw we don't support it on
drm/radeon: Add RADEON_INFO_VA_UNMAP_WORKING query