efi: Create a 64-bit app

Most modern platforms use 64-bit EFI so it is useful to have a U-Boot app
that runs under that. Add a (non-functional) build for this.

Note that --whole-archive causes the gcc 9.2 linker to crash, so disable
this for now. Once this is resolved, things should work.

For now, avoid mentioning the documentation for the 64-bit app, since it
does not work.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/board/efi/efi-x86_app/MAINTAINERS b/board/efi/efi-x86_app/MAINTAINERS
index fb8a6b1..b292811 100644
--- a/board/efi/efi-x86_app/MAINTAINERS
+++ b/board/efi/efi-x86_app/MAINTAINERS
@@ -1,6 +1,13 @@
-EFI-X86_APP BOARD
+EFI-X86_APP32 BOARD
 M:	Simon Glass <sjg@chromium.org>
 S:	Maintained
 F:	board/efi/efi-x86_app/
 F:	include/configs/efi-x86_app.h
-F:	configs/efi-x86_app_defconfig
+F:	configs/efi-x86_app32_defconfig
+
+EFI-X86_APP64 BOARD
+M:	Simon Glass <sjg@chromium.org>
+S:	Maintained
+F:	board/efi/efi-x86_app/
+F:	include/configs/efi-x86_app.h
+F:	configs/efi-x86_app64_defconfig