Fix output format in system_timer.c

Change-Id: Id05eebb811d4c23c6a2bfdfb4762bb659b97a4bf
Signed-off-by: John Tsichritzis <john.tsichritzis@arm.com>
diff --git a/drivers/arm/timer/system_timer.c b/drivers/arm/timer/system_timer.c
index 3415e41..6cc3cef 100644
--- a/drivers/arm/timer/system_timer.c
+++ b/drivers/arm/timer/system_timer.c
@@ -44,7 +44,7 @@
 	if (count_val < mmio_read_64(g_systimer_base + CNTPCT_LO))
 		panic();
 
-	VERBOSE("%s : interrupt requested at sys_counter: %lld "
+	VERBOSE("%s : interrupt requested at sys_counter: %llu "
 		"time_out_ms: %ld\n", __func__, count_val, time_out_ms);
 
 	return 0;