airo: fix endianness bug in ->dBm handling

airo_translate_scan() reads BSSListRid directly, does _not_ byteswap
and uses ->dBm (__le16) as host-endian.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: John W. Linville <linville@tuxdriver.com>