uhd: allow the non-uhd to still compile unchanged

The missing methods are not implemented and simply return. They
didn't exist in the first place.

Signed-off-by: Thomas Tsou <ttsou@vt.edu>

git-svn-id: http://wush.net/svn/range/software/public/openbts/trunk@2642 19bc5d8c-e614-43d4-8b26-e1612bc8e597

Transceiver52M/USRPDevice.h

@@ -123,6 +123,9 @@ private:
   /** Stop the USRP */
   bool stop();
 
+  /** Set priority not supported */
+  void setPriority() { return; }
+
   /**
 	Read samples from the USRP.
 	@param buf preallocated buf to contain read result