On atomic drivers we can dig out the primary plane rotation from the
plane state instead of looking at the legacy crtc->invert_dimensions
flag. The flag is not set by anyone except omapdrm, and it would be
racy to set it the same way in the atomic helpers.

v2: Kill crtc->invert_dimensions totally since omap is state based
    already and no one else ever used it (Matt)

Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1445009919-22746-1-git-send-email-ville.syrjala@linux.intel.comReviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>