drm/doc: integrate drm_crtc.c kerneldoc

And do a quick pass to adjust them to the last few (years?) of changes
...

This time actually compile-tested ;-)

Reviewed-by: Rob Clark <rob@ti.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

Documentation/DocBook/drm.tmpl

@@ -1609,6 +1609,10 @@ void intel_crt_init(struct drm_device *dev)
         make its properties available to applications.
       </para>
     </sect2>
+    <sect2>
+      <title>KMS API Functions</title>
+!Edrivers/gpu/drm/drm_crtc.c
+    </sect2>
   </sect1>
 
   <!-- Internals: kms helper functions -->