MFC r330970, r331067, r331767, r331852, r331858

r330970:
libefi: UEFI_BOOT_VAR_GUID duplicates EFI_GLOBAL_VARIABLE

Drop UEFI_BOOT_VAR_GUID and use EFI_GLOBAL_VARIABLE.

r331067:
Only print boot order / boot current if we can get the variables from
the loader. Some UEFI implementations don't return all of them.

Sponsored by: Netflix

r331767:
efinet: Do not return only if ReceiveFilter fails

If the network interface or the uefi implementation do not support the
ReceiveFilter interface do not return only and just print a message.
U-Boot doesn't support is and likely never will. Also even if this fails
it doesn't mean that network in EFI isn't supported.

r331852:
fwohcireg.h is 99% the same between the boot loader and the
kernel. Delete it and fix up the 1% difference because there's no need
for them to be different.

r331858:
The Uninorth ID was really for Uninorth 2.