genirq: Plug race in report_bad_irq()

We cannot walk the action chain unlocked. Even if IRQ_INPROGRESS is
set an action can be removed and we follow a null pointer. It's safe
to take the lock there, because the code which removes the action will
call synchronize_irq() which waits unlocked for IRQ_INPROGRESS going
away.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>