irq_work: Introduce arch_irq_work_has_interrupt()

The nohz full code needs irq work to trigger its own interrupt so that
the subsystem can work even when the tick is stopped.

Lets introduce arch_irq_work_has_interrupt() that archs can override to
tell about their support for this ability.

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

include/linux/irq_work.h

@@ -42,6 +42,8 @@ void irq_work_run(void);
 void irq_work_sync(struct irq_work *work);
 
 #ifdef CONFIG_IRQ_WORK
+#include <asm/irq_work.h>
+
 bool irq_work_needs_cpu(void);
 #else
 static inline bool irq_work_needs_cpu(void) { return false; }