drm: export the DRM permission check code

This way drm_ioctl_permit() can be used by drivers

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 4717449..3b0c50f 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -887,6 +887,7 @@
 /*@{*/
 
 				/* Driver support (drm_drv.h) */
+extern int drm_ioctl_permit(u32 flags, struct drm_file *file_priv);
 extern long drm_ioctl(struct file *filp,
 		      unsigned int cmd, unsigned long arg);
 extern long drm_compat_ioctl(struct file *filp,