[ARM] mmp: rename irq.c to irq-pxa168.c to allow other SoC IRQ chips

# Makefile for Marvell's PXA168 processors line

#

obj-y				+= common.o clock.o devices.o irq.o time.o

obj-y				+= common.o clock.o devices.o time.o

# SoC support

obj-$(CONFIG_CPU_PXA168)	+= pxa168.o

obj-$(CONFIG_CPU_PXA910)	+= pxa910.o

obj-$(CONFIG_CPU_PXA168)	+= pxa168.o irq-pxa168.o

obj-$(CONFIG_CPU_PXA910)	+= pxa910.o irq-pxa168.o

# board support

obj-$(CONFIG_MACH_ASPENITE)	+= aspenite.o