drm/atomic: Only update crtc->x/y if it's part of the state, v2.

Universal planes may not be assigned to the current crtc, so only
update crtc->x/y when the primary is part of the state and bound
to the current crtc.

Changes since v1:
- Add the crtc check.

Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>