This is a patch from Simon Glass. U-Boot clears the display
when it starts up, but was asking the VESA driver to do the
same, needlessly; this patch avoids the latter.

A further patch is also included, which provides a better
message when jumping into long mode on the SPL (64-bit) target,
dumping it on the serial console instead of using printf.

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

U-Boot was hanging on hardware, but not Qemu. This is because on
the machines tested, namely the X200 and E6230 laptops supported
in Libreboot, the UART was disabled from coreboot.

This U-Boot patch from Simon Glass works around the issue by
silently disabling the UART when it isn't there. Instead,
output is sent to the display and U-Boot no longer hangs.

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>