Restart the beacon timers only if the beacon
was already configured. Otherwise beacons timers
are restarted unnecessarily in unassociated state too.

Cc: stable@kernel.org
Signed-off-by: NRajkumar Manoharan <rmanoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>