Set rotation reference directly via internal API.

Note that the original code would first set the rotation reference value
stored in the Xf, then later unconditionally overwrite it according to
the border setting.  The new code only ports the second part.  Perhaps
there was a bug in the original code....

Change-Id: I15b6839e9a58e8070a43db70e1a88b42ed99f2d8