x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h

x86, irq: Move IOAPIC related declarations from hw_irq.h into io_apic.h

Clean up code by moving IOAPIC related declarations from hw_irq.h into
io_apic.h.

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Christian Gmeiner <christian.gmeiner@gmail.com>
Cc: Aubrey <aubrey.li@linux.intel.com>
Cc: Ryan Desfosses <ryan@desfo.org>
Cc: Quentin Lambert <lambert.quentin@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: http://lkml.kernel.org/r/1414397531-28254-14-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>