irq: Don't re-enable interrupts at the end of irq_exit

Commit 74eed0163d0def3fce27228d9ccf3d36e207b286
"irq: Ensure irq_exit() code runs with interrupts disabled"
restore interrupts flags in the end of irq_exit() for archs
that don't define __ARCH_IRQ_EXIT_IRQS_DISABLED.

However always returning from irq_exit() with interrupts
disabled should not be a problem for these archs. Prior to
this commit this was already happening anytime we processed
pending softirqs anyway.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

kernel/softirq.c

@@ -334,9 +334,7 @@ static inline void invoke_softirq(void)
 void irq_exit(void)
 {
 #ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
-	unsigned long flags;
-
-	local_irq_save(flags);
+	local_irq_disable();
 #else
 	WARN_ON_ONCE(!irqs_disabled());
 #endif
@@ -353,9 +351,6 @@ void irq_exit(void)
 		tick_nohz_irq_exit();
 #endif
 	rcu_irq_exit();
-#ifndef __ARCH_IRQ_EXIT_IRQS_DISABLED
-	local_irq_restore(flags);
-#endif
 }
 
 /*