MIPS: Malta: Fix section mismatch.

  LD      arch/mips/pci/built-in.o
WARNING: arch/mips/pci/built-in.o(.devinit.text+0x2a0): Section mismatch in reference from the function malta_piix_func0_fixup() to the variable .init.data:pci_irq
The function __devinit malta_piix_func0_fixup() references
a variable __initdata pci_irq.
If pci_irq is only used by malta_piix_func0_fixup then
annotate pci_irq with a matching annotation.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>