x86/irq: Replace numeric constant

Use the proper define instead of 0.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Link: http://lkml.kernel.org/r/20150802203609.385495420@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --cc arch/x86/kernel/irq.c
Simple merge