[U-Boot] EFI loader support largely enabled

Hey all,

What I mean by the subject is that with the EFI loader patches enabled U-Boot itself (not SPL) now includes the EFI loader and required bits on ARM/aarch64. This is in general I think a good thing. I've however disabled it on a few boards due to size constraints. This is an average gain of ~12KiB in U-Boot proper. I fully expect a number of platform patches opting out of this support due to it just not being a real usecase and I am agreeable to talking about making it not enabled by default. So, lets kick things off.