drm: extract drm_gem_object_init

This function can be used by drivers who allocate the drm gem object
on their own. No functional change in here, just preparation.

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Acked-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index 2f3b3a0..b3b57b5 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1432,6 +1432,8 @@
 void drm_gem_object_free_unlocked(struct kref *kref);
 struct drm_gem_object *drm_gem_object_alloc(struct drm_device *dev,
 					    size_t size);
+int drm_gem_object_init(struct drm_device *dev,
+			struct drm_gem_object *obj, size_t size);
 void drm_gem_object_handle_free(struct kref *kref);
 void drm_gem_vm_open(struct vm_area_struct *vma);
 void drm_gem_vm_close(struct vm_area_struct *vma);