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_crtc.c

@@ -415,11 +415,12 @@ int drm_mode_getcrtc(struct drm_device *dev,
 }
 
 /**
- * drm_mode_set_config_internal - helper to call ->set_config
+ * drm_mode_set_config_internal - helper to call &drm_mode_config_funcs.set_config
  * @set: modeset config to set
  *
- * This is a little helper to wrap internal calls to the ->set_config driver
- * interface. The only thing it adds is correct refcounting dance.
+ * This is a little helper to wrap internal calls to the
+ * &drm_mode_config_funcs.set_config driver interface. The only thing it adds is
+ * correct refcounting dance.
  *
  * Returns:
  * Zero on success, negative errno on failure.