nios2: Build infrastructure

This patch adds Makefile and Kconfig files required for building a
nios2 kernel.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

arch/nios2/mm/Makefile

@@ -0,0 +1,14 @@
+#
+# Makefile for the Nios2-specific parts of the memory manager.
+#
+
+obj-y	+= cacheflush.o
+obj-y	+= dma-mapping.o
+obj-y	+= extable.o
+obj-y	+= fault.o
+obj-y	+= init.o
+obj-y	+= ioremap.o
+obj-y	+= mmu_context.o
+obj-y	+= pgtable.o
+obj-y	+= tlb.o
+obj-y	+= uaccess.o