Otherwise, you have to press enter to boot your distro.

With this, a timeout is created. After a number of seconds,
which can be reconfigured, the first option selected will be booted,
when generating a bootflow menu.

The timeout is disabled when you navigate the menu; it only
kicks in if you don't input anything on the keyboard.

More information about how this works is in the U-Boot patches,
within this patch. I've set the timeout to 8 seconds.

Signed-off-by: Leah Rowe <leah@libreboot.org>

It's a new experimental payload in Libreboot, so we may aswell
start with the very latest release of U-Boot.

Signed-off-by: Leah Rowe <leah@libreboot.org>

NOTE: Support added for xarch target x86_64-elf,
but U-Boot failed to build with this error:

OBJCOPY lib/efi_loader/helloworld.efi
x86_64-elf-objcopy: lib/efi_loader/helloworld_efi.so: invalid bfd target
make[2]: *** [scripts/Makefile.lib:476: lib/efi_loader/helloworld.efi] Error 1

Since I'm building U-Boot for x86_64 *on* an x86-64
host, and since that is currently the recommended type
of machine to use for lbmk development, and since the
other x86 payloads currently don't cross compile anyway,
this is an acceptable compromise for now. This is because
at present, I'm not making U-Boot the primary payload on x86,
instead preferring to chain it from GRUB and SeaBIOS.

The target.cfg file for x86 u-boot shows xarch/xtree commented.
Uncomment these to compile on crossgcc instead of hostcc.

I mention 64-bit because I initially did this first, but decided
to do 32-bit first. I'll work on the 64-bit one next (SPL).

It's only enabled in QEMU for now.

Signed-off-by: Leah Rowe <leah@libreboot.org>