x86: rename discontig_32.c to numa_32.c

name it in line with its purpose.
Signed-off-by: NYinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

arch/x86/mm/Makefile

@@ -13,12 +13,8 @@ obj-$(CONFIG_MMIOTRACE)		+= mmiotrace.o
 mmiotrace-y			:= pf_in.o mmio-mod.o
 obj-$(CONFIG_MMIOTRACE_TEST)	+= testmmiotrace.o
 
-ifeq ($(CONFIG_X86_32),y)
-obj-$(CONFIG_NUMA)		+= discontig_32.o
-else
-obj-$(CONFIG_NUMA)		+= numa_64.o
+obj-$(CONFIG_NUMA)		+= numa_$(BITS).o
 obj-$(CONFIG_K8_NUMA)		+= k8topology_64.o
-endif
 obj-$(CONFIG_ACPI_NUMA)		+= srat_$(BITS).o
 
 obj-$(CONFIG_MEMTEST)		+= memtest.o