adapt the urtwn(4) driver to use the new files. The firmware files were
extracted from the Linux driver at www.realtek.com, version 0005.1230.2011
and the license permits redistribution without modification.
While I'm here, install the files in /libdata/firmware/if_urtwn, like
most of the other network adapter firmware.
urtwn(4) can now operate without needing external files installed. Tested
on my Edimax adapter.