s390/spinlock: remove confusing comment in arch_spin_lock_wait

arch_spin_lock_wait does not take steal time into consideration.
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/lib/spinlock.c

@@ -242,7 +242,6 @@ static inline void arch_spin_lock_classic(arch_spinlock_t *lp)
 
 void arch_spin_lock_wait(arch_spinlock_t *lp)
 {
-	/* Use classic spinlocks + niai if the steal time is >= 10% */
 	if (test_cpu_flag(CIF_DEDICATED_CPU))
 		arch_spin_lock_queued(lp);
 	else