arm64: Build infrastructure

This patch adds Makefile and Kconfig files required for building an
AArch64 kernel.

Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Olof Johansson <olof@lixom.net>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/arm64/mm/Makefile

@@ -0,0 +1,4 @@
+obj-y				:= dma-mapping.o extable.o fault.o init.o \
+				   cache.o copypage.o flush.o \
+				   ioremap.o mmap.o pgd.o mmu.o \
+				   context.o tlb.o proc.o