[nrf fromtree] drivers: timer: nrf_grtc_timer: Fix for random hangs

d599e2b removed early return from sys_clock_timeout_handler if
current counter value is less than cc_val. It seems that this return is
needed as after the removal some stress tests which were using system
timers heavily started to hang.

Signed-off-by: Krzysztof Chruściński <[email protected]>
(cherry picked from commit af3c8b9)

Author: nordic-krch

drivers/timer/nrf_grtc_timer.c

@@ -140,6 +140,11 @@ static void sys_clock_timeout_handler(int32_t id, uint64_t cc_val, void *p_conte
 	ARG_UNUSED(id);
 	ARG_UNUSED(p_context);
 	uint64_t dticks;
+	uint64_t now = counter();
+
+	if (unlikely(now < cc_val)) {
+		return;
+	}
 
 	dticks = counter_sub(cc_val, last_count) / CYC_PER_TICK;