clocksource/drivers/timer-rtl-otto: Do not interfere with interrupts

During normal operation the timers are reprogrammed including an
interrupt acknowledgement. This has no effect as the whole timer
is setup from scratch afterwards. Especially in an interrupt this
has already been done by rttm_timer_interrupt().

Change the behaviour as follows:

- Use rttm_disable_timer() during reprogramming
- Keep rttm_stop_timer() for all other use cases.

Downstream has already tested and confirmed a patch. See
openwrt/openwrt#19468
https://forum.openwrt.org/t/support-for-rtl838x-based-managed-switches/57875/3788

Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Tested-by: Stephen Howell <howels@allthatwemight.be>
Tested-by: Bjørn Mork <bjorn@mork.no>
Link: https://lore.kernel.org/r/20250804080328.2609287-4-markus.stockhausen@gmx.de

Author: plappermaul

drivers/clocksource/timer-rtl-otto.c

@@ -141,7 +141,7 @@ static int rttm_next_event(unsigned long delta, struct clock_event_device *clkev
 
 	RTTM_DEBUG(to->of_base.base);
 	rttm_bounce_timer(to->of_base.base, RTTM_CTRL_COUNTER);
-	rttm_stop_timer(to->of_base.base);
+	rttm_disable_timer(to->of_base.base);
 	rttm_set_period(to->of_base.base, delta);
 	rttm_start_timer(to, RTTM_CTRL_COUNTER);
 
@@ -154,7 +154,7 @@ static int rttm_state_oneshot(struct clock_event_device *clkevt)
 
 	RTTM_DEBUG(to->of_base.base);
 	rttm_bounce_timer(to->of_base.base, RTTM_CTRL_COUNTER);
-	rttm_stop_timer(to->of_base.base);
+	rttm_disable_timer(to->of_base.base);
 	rttm_set_period(to->of_base.base, RTTM_TICKS_PER_SEC / HZ);
 	rttm_start_timer(to, RTTM_CTRL_COUNTER);
 
@@ -167,7 +167,7 @@ static int rttm_state_periodic(struct clock_event_device *clkevt)
 
 	RTTM_DEBUG(to->of_base.base);
 	rttm_bounce_timer(to->of_base.base, RTTM_CTRL_TIMER);
-	rttm_stop_timer(to->of_base.base);
+	rttm_disable_timer(to->of_base.base);
 	rttm_set_period(to->of_base.base, RTTM_TICKS_PER_SEC / HZ);
 	rttm_start_timer(to, RTTM_CTRL_TIMER);