drm/i915: Don't enable the cursor on a disable pipe

drm/i915: Don't enable the cursor on a disable pipe

commit f2f5f771c5fc0fa252cde3d0d0452dcc785cc17a upstream.

On HSW enabling a plane on a disabled pipe may hang the entire system.
And there's no good reason for doing it ever, so just don't.

v2: Move the crtc active checks to intel_crtc_cursor_{set,move} to
    avoid confusing people during modeset

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Tested-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>