posix-cpu-timers: Remove lockdep_assert_irqs_disabled()

The lockdep_assert_irqs_disabled() was a BUG_ON() statement in the
beginning and it was added just before the "spin_lock(siglock)"
statement to ensure this lock was taken with disabled interrupts.

This is no longer the case: the siglock is acquired via
lock_task_sighand() and this function already disables the interrupts.
The lock is also acquired before this "lockdep_assert_irqs_disabled" so
it is best to remove it.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <frederic@kernel.org>
Link: https://lkml.kernel.org/r20180504152548.7166-1-bigeasy@linutronix.de

kernel/time/posix-cpu-timers.c

@@ -604,7 +604,6 @@ static int posix_cpu_timer_set(struct k_itimer *timer, int timer_flags,
 	/*
 	 * Disarm any old timer after extracting its expiry time.
 	 */
-	lockdep_assert_irqs_disabled();
 
 	ret = 0;
 	old_incr = timer->it.cpu.incr;
@@ -1049,7 +1048,6 @@ static void posix_cpu_timer_rearm(struct k_itimer *timer)
 	/*
 	 * Now re-arm for the new expiry time.
 	 */
-	lockdep_assert_irqs_disabled();
 	arm_timer(timer);
 unlock:
 	unlock_task_sighand(p, &flags);