MN10300: ASB2305's PCI code needs the definition of XIRQ1

MN10300: ASB2305's PCI code needs the definition of XIRQ1

The code for PCI in the ASB2305 needs the definition of XIRQ1 from proc/irq.h
otherwise the following error appears:

  arch/mn10300/unit-asb2305/pci.c: In function 'unit_pci_init':
  arch/mn10300/unit-asb2305/pci.c:481: error: 'XIRQ1' undeclared (first use in this function)
  arch/mn10300/unit-asb2305/pci.c:481: error: (Each undeclared identifier is reported only once
  arch/mn10300/unit-asb2305/pci.c:481: error: for each function it appears in.)

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ken Cox <jkc@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>