drm/i915: Add overlooked plane disable tracepoint into intel_crtc_disable_planes()

intel_crtc_disable_planes() disables the planes so it should
trigger the appropriate tracepoint.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190206204910.13965-3-ville.syrjala@linux.intel.com


Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>