Staging: wlags49_h2: fix up signal levels

Adjusts the signal levels reported by the wlags49_h2 and wlags49_h25 staging
drivers. With the constants supplied by Agere the signal levels are always
poor, even in close proximity to the AP. The signals are now measured with
a real device. 100% for close proximity to the AP, 0% for the noice floor.
Now the levels shown by the NetworkManager gauge make sense.

Some magic numbers in the related code are replaced by the correct constants
from the wireless extension interface (wireless.h). Also the flag IW_QUAL_DBM
is now set, as specified in the wireless.h header file.

Signed-off-by: Henk de Groot <pe1dnn@amsat.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>