hrtimer: Rely on rt_task() for DL tasks too

Checking dl_task() is redundant as rt_task() returns true for deadline
tasks too.

Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20230123173206.6764-2-dave@stgolabs.net

Author: Davidlohr Bueso

kernel/time/hrtimer.c

@@ -2089,7 +2089,7 @@ long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
 	u64 slack;
 
 	slack = current->timer_slack_ns;
-	if (dl_task(current) || rt_task(current))
+	if (rt_task(current))
 		slack = 0;
 
 	hrtimer_init_sleeper_on_stack(&t, clockid, mode);