arm64: add arch/arm64/Kbuild

Use the standard obj-y form to specify the sub-directories under
arch/arm64/. No functional change intended.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Will Deacon <will@kernel.org>
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 61de992..dcbbd53 100644
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -136,11 +136,7 @@
 
 export	TEXT_OFFSET GZFLAGS
 
-core-y		+= arch/arm64/kernel/ arch/arm64/mm/
-core-$(CONFIG_NET) += arch/arm64/net/
-core-$(CONFIG_KVM) += arch/arm64/kvm/
-core-$(CONFIG_XEN) += arch/arm64/xen/
-core-$(CONFIG_CRYPTO) += arch/arm64/crypto/
+core-y		+= arch/arm64/
 libs-y		:= arch/arm64/lib/ $(libs-y)
 core-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a