* Use the same function for domaintxfmrf in both highbd and lowbd
  cases
* Move an assertion out of a loop in
  apply_selfguided_restoration_highbd, to match the lowbd case

No change to output, but a decoder speed improvement of ~3.5%
(roughly independent of bitrate) with loop-restoration on a
10bpp sample.

Change-Id: I970a3bb8f1c6b0ac60aa4a6fe4e7f54d1e6c1452