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/doc/develop/uefi/u-boot_on_efi.rst b/doc/develop/uefi/u-boot_on_efi.rst
index 8856af3..f275a52 100644
--- a/doc/develop/uefi/u-boot_on_efi.rst
+++ b/doc/develop/uefi/u-boot_on_efi.rst
@@ -48,10 +48,10 @@
 opt for using QEMU [1] and the OVMF [2], as detailed below.
 
 To build U-Boot as an EFI application (32-bit EFI required), enable CONFIG_EFI
-and CONFIG_EFI_APP. The efi-x86_app config (efi-x86_app_defconfig) is set up
+and CONFIG_EFI_APP. The efi-x86_app config (efi-x86_app32_defconfig) is set up
 for this. Just build U-Boot as normal, e.g.::
 
-   make efi-x86_app_defconfig
+   make efi-x86_app32_defconfig
    make
 
 To build U-Boot as an EFI payload (32-bit or 64-bit EFI can be used), enable
@@ -261,7 +261,7 @@
 
 - Add ARM support
 
-- Add 64-bit application support
+- Add 64-bit application support (in progress)
 
 - Figure out how to solve the interrupt problem