efi: arm: Add aarch64 EFI app support

Add support for EFI apps on aarch64. This includes start-up and relocation
code plus a link script.

Signed-off-by: Simon Glass <sjg@chromium.org>
[agraf: add kconfig dep]
Signed-off-by: Alexander Graf <agraf@suse.de>
diff --git a/cmd/Kconfig b/cmd/Kconfig
index a1ce4b7..501ac17 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -183,7 +183,7 @@
 
 config CMD_BOOTEFI_HELLO
 	bool "Allow booting a standard EFI hello world for testing"
-	depends on CMD_BOOTEFI && ARM && !ARM64
+	depends on CMD_BOOTEFI && ARM
 	help
 	  This adds a standard EFI hello world application to U-Boot so that
 	  it can be used with the 'bootefi hello' command. This is useful