Move dmapool.c to mm/ directory

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
diff --git a/mm/Makefile b/mm/Makefile
index 5c0b0ea..e222cc5 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -15,6 +15,7 @@
 
 obj-$(CONFIG_BOUNCE)	+= bounce.o
 obj-$(CONFIG_SWAP)	+= page_io.o swap_state.o swapfile.o thrash.o
+obj-$(CONFIG_HAS_DMA)	+= dmapool.o
 obj-$(CONFIG_HUGETLBFS)	+= hugetlb.o
 obj-$(CONFIG_NUMA) 	+= mempolicy.o
 obj-$(CONFIG_SPARSEMEM)	+= sparse.o