drm/core: Use recommened kerneldoc for struct member refs

I just learned that &struct_name.member_name works and looks pretty
even. It doesn't (yet) link to the member directly though, which would
be really good for big structures or vfunc tables (where the
per-member kerneldoc tends to be long).

Also some minor drive-by polish where it makes sense, I read a lot
of docs ...

v2: Review from Gustavo.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170125062657.19270-6-daniel.vetter@ffwll.ch
diff --git a/include/drm/drm_drv.h b/include/drm/drm_drv.h
index 34ece39..5ab2459 100644
--- a/include/drm/drm_drv.h
+++ b/include/drm/drm_drv.h
@@ -314,7 +314,7 @@ struct drm_driver {
 	/**
 	 * @gem_free_object_unlocked: deconstructor for drm_gem_objects
 	 *
-	 * This is for drivers which are not encumbered with dev->struct_mutex
+	 * This is for drivers which are not encumbered with &drm_device.struct_mutex
 	 * legacy locking schemes. Use this hook instead of @gem_free_object.
 	 */
 	void (*gem_free_object_unlocked) (struct drm_gem_object *obj);