[PATCH] ipw2200: generates a scan event after a scan has completed

The patch make ipw2200 generate the scan event every time a scan has
completed, so that user space know when to get fresh results.
Dan Williams would like to go towards this model in Network Manager
rather than having to poll.

Signed-off-by: Jean Tourrilhes <jt@hpl.hp.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>