brcmsmac: main: Eliminate empty brcms_c_down_del_timer()

This function does nothing so remove it. This addresses the following
coccicheck warning:

drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c:5103:6-15:
Unneeded variable: "callbacks". Return "0" on line 5105
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200910140446.1168049-1-yanaijie@huawei.com
Link: https://lore.kernel.org/r/20200910140455.1168174-1-yanaijie@huawei.com

drivers/net/wireless/broadcom/brcm80211/brcmsmac/main.c

@@ -5085,13 +5085,6 @@ int brcms_c_up(struct brcms_c_info *wlc)
 	return 0;
 }
 
-static uint brcms_c_down_del_timer(struct brcms_c_info *wlc)
-{
-	uint callbacks = 0;
-
-	return callbacks;
-}
-
 static int brcms_b_bmac_down_prep(struct brcms_hardware *wlc_hw)
 {
 	bool dev_gone;
@@ -5201,8 +5194,6 @@ uint brcms_c_down(struct brcms_c_info *wlc)
 			callbacks++;
 		wlc->WDarmed = false;
 	}
-	/* cancel all other timers */
-	callbacks += brcms_c_down_del_timer(wlc);
 
 	wlc->pub->up = false;