mac80211: Restart STA timers only on associated state

BugLink: http://bugs.launchpad.net/bugs/823296

commit 676b58c27475a9defccc025fea1cbd2b141ee539 upstream.

A panic was observed when the device is failed to resume properly,
and there are no running interfaces. ieee80211_reconfig tries
to restart STA timers on unassociated state.

Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>