ipw2100: Fix 'Driver using old /proc/net/wireless...' message

Wireless extensions moved the get_wireless_stats handler from being
in net_device into wireless_handler.

A prior instance of this patch resolved the issue for the ipw2200.
This one fixes it for the ipw2100.
Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org>
Signed-off-by: James Ketrenos <jketreno@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>