ipw2200 makes extensive use of background scanning when unassociated or
down.  Unfortunately, the firmware sends scan completed events many
times per second, which the driver pushes directly up to userspace.
This needlessly wakes up processes listening for wireless events many
times per second.  Batch together scan completed events for
non-user-requested scans and send them up to userspace every 4 seconds.
Scan completed events resulting from an SIOCSIWSCAN call are pushed up
without delay.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>