drm: don't check modeset locks in panic handler

Since we know that locking is broken in that case and it's more
important to not flood the dmesg with random gunk.

Cc: Dave Airlie <airlied@gmail.com>
Cc: Borislav Petkov <bp@alien8.de>
References: http://lkml.kernel.org/r/20130502000206.GH15623@pd.tnic
Cc: stable@vger.kernel.org
Reported-and-tested-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_crtc.c

@@ -78,6 +78,10 @@ void drm_warn_on_modeset_not_all_locked(struct drm_device *dev)
 {
 	struct drm_crtc *crtc;
 
+	/* Locking is currently fubar in the panic handler. */
+	if (oops_in_progress)
+		return;
+
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
 		WARN_ON(!mutex_is_locked(&crtc->mutex));