brcmsmac: increase timer reference count for new timers only

On hardware reintialization reference count of
already existing timers would be increased again.
This leads to problems on module unloading.

Cc: stable@vger.kernel.org
Reviewed-by: Pieter-Paul Giesberts <pieterpg@broadcom.com>
Reviewed-by: Hante Meuleman <meuleman@broadcom.com>
Reviewed-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: Piotr Haber <phaber@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/brcm80211/brcmsmac/mac80211_if.c

@@ -1407,9 +1407,10 @@ void brcms_add_timer(struct brcms_timer *t, uint ms, int periodic)
 #endif
 	t->ms = ms;
 	t->periodic = (bool) periodic;
+	if (!t->set) {
 		t->set = true;
-
 		atomic_inc(&t->wl->callbacks);
+	}
 
 	ieee80211_queue_delayed_work(hw, &t->dly_wrk, msecs_to_jiffies(ms));
 }