powerpc: Rename dma_64.c to dma.c

This is in preparation for the merge of the 32 and 64-bit
dma code in arch/powerpc.
Signed-off-by: Becky Bruce <becky.bruce@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

arch/powerpc/kernel/Makefile

@@ -73,7 +73,7 @@ obj-y				+= time.o prom.o traps.o setup-common.o \
 				   udbg.o misc.o io.o \
 				   misc_$(CONFIG_WORD_SIZE).o
 obj-$(CONFIG_PPC32)		+= entry_32.o setup_32.o
-obj-$(CONFIG_PPC64)		+= dma_64.o iommu.o
+obj-$(CONFIG_PPC64)		+= dma.o iommu.o
 obj-$(CONFIG_KGDB)		+= kgdb.o
 obj-$(CONFIG_PPC_MULTIPLATFORM)	+= prom_init.o
 obj-$(CONFIG_MODULES)		+= ppc_ksyms.o