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

Signed-off-by: NEric Miao <eric.y.miao@gmail.com>

arch/arm/mach-mmp/Makefile

@@ -2,11 +2,11 @@
 # 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