drm/kms-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 Eric.

Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170125062657.19270-4-daniel.vetter@ffwll.ch

drivers/gpu/drm/drm_dumb_buffers.c

@@ -42,8 +42,8 @@
  * create dumb buffers suitable for scanout, which can then be used to create
  * KMS frame buffers.
  *
- * To support dumb objects drivers must implement the dumb_create,
- * dumb_destroy and dumb_map_offset operations from &struct drm_driver. See
+ * To support dumb objects drivers must implement the &drm_driver.dumb_create,
+ * &drm_driver.dumb_destroy and &drm_driver.dumb_map_offset operations. See
  * there for further details.
  *
  * Note that dumb objects may not be used for gpu acceleration, as has been