[PATCH] ipw2200: Add signal level to iwlist scan output

This patch does two things. It uses the parameter IW_QUAL_DBM which is new
in WE-19 to cause signal level and noise to be reported in dBm by the
wireless tools. It also defines the signal level as an unsigned integer
so that the signal level will be reported by iwlist iface scan.

Signed-off-by: Bill Moss <bmoss@clemson.edu>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>