MIPS: Move arch_get_unmapped_area and gang to new file.

It never really belonged into syscall.c and it's about to become well more
complex.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index eb44636..4d8c162 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -3,7 +3,8 @@
 #
 
 obj-y				+= cache.o dma-default.o extable.o fault.o \
-				   init.o tlbex.o tlbex-fault.o uasm.o page.o
+				   init.o mmap.o tlbex.o tlbex-fault.o uasm.o \
+				   page.o
 
 obj-$(CONFIG_32BIT)		+= ioremap.o pgtable-32.o
 obj-$(CONFIG_64BIT)		+= pgtable-64.o