power: reset: ltc2952: remove unused variable

Fix gcc '-Wunused-but-set-variable' warning:
drivers/power/reset/ltc2952-poweroff.c:97:16: warning: variable
‘overruns’ set but not used [-Wunused-but-set-variable]
unsigned long overruns;

Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: Hongbo Yao <[e-mail]>
Signed-off-by: Sebastian Reichel <[e-mail]>

drivers/power/reset/ltc2952-poweroff.c

···
 {
 	ktime_t now;
 	int state;
-	unsigned long overruns;
 	struct ltc2952_poweroff *data = to_ltc2952(timer, timer_wde);
 
 	if (data->kernel_panic)
···
 	gpiod_set_value(data->gpio_watchdog, !state);
 
 	now = hrtimer_cb_get_time(timer);
-	overruns = hrtimer_forward(timer, now, data->wde_interval);
+	hrtimer_forward(timer, now, data->wde_interval);
 
 	return HRTIMER_RESTART;
 }