IEEE 802.11b/g WLAN device, ported from OpenBSD by FUKAUMI Naoki:
http://mail-index.NetBSD.org/current-users/2010/05/28/msg013570.html
Slightly modified by me to use recently added config_mountroot(9)
to defer some device initialization until mountroot for firmload(9).
Tested on Sharp W-ZERO3 WS003SH with internal WLAN.
Note currently we cannot redistribute firmware files for upgt(4) so
they have to be downloaded and copied into /libdata/firmware/upgt manually.
See upgt(4) man page about firmware details.