futex: Remove a PREEMPT_RT_FULL reference.

Earlier the PREEMPT_RT patch had a PREEMPT_RT_FULL and PREEMPT_RT_BASE
Kconfig option. The latter was a subset of the functionality that was
enabled with PREEMPT_RT_FULL and was mainly useful for debugging.

During the merging efforts the two Kconfig options were abandoned in the
v5.4.3-rt1 release and since then there is only PREEMPT_RT which enables
the full features set (as PREEMPT_RT_FULL did in earlier releases).

Replace the PREEMPT_RT_FULL reference with PREEMPT_RT.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/r/YnvWUvq1vpqCfCU7@linutronix.de

Author: Sebastian Andrzej Siewior

kernel/futex/pi.c

@@ -1005,7 +1005,7 @@ int futex_lock_pi(u32 __user *uaddr, unsigned int flags, ktime_t *time, int tryl
 	rt_mutex_init_waiter(&rt_waiter);
 
 	/*
-	 * On PREEMPT_RT_FULL, when hb->lock becomes an rt_mutex, we must not
+	 * On PREEMPT_RT, when hb->lock becomes an rt_mutex, we must not
 	 * hold it while doing rt_mutex_start_proxy(), because then it will
 	 * include hb->lock in the blocking chain, even through we'll not in
 	 * fact hold it while blocking. This will lead it to report -EDEADLK