posix-timers: Avoid direct access to hrtimer clockbase

The field timer->base->get_time is a private implementation detail and
should not be accessed outside of the hrtimer core.

Switch to the equivalent helpers.

Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/all/20250821-hrtimer-cleanup-get_time-v2-1-3ae822e5bfbd@linutronix.de

Author: t-8ch

kernel/time/posix-timers.c

@@ -299,8 +299,7 @@ static void common_hrtimer_rearm(struct k_itimer *timr)
 {
 	struct hrtimer *timer = &timr->it.real.timer;
 
-	timr->it_overrun += hrtimer_forward(timer, timer->base->get_time(),
-					    timr->it_interval);
+	timr->it_overrun += hrtimer_forward_now(timer, timr->it_interval);
 	hrtimer_restart(timer);
 }
 
@@ -825,7 +824,7 @@ static void common_hrtimer_arm(struct k_itimer *timr, ktime_t expires,
 	hrtimer_setup(&timr->it.real.timer, posix_timer_fn, timr->it_clock, mode);
 
 	if (!absolute)
-		expires = ktime_add_safe(expires, timer->base->get_time());
+		expires = ktime_add_safe(expires, hrtimer_cb_get_time(timer));
 	hrtimer_set_expires(timer, expires);
 
 	if (!sigev_none)