[L] Change in coreboot[master]: drivers/efi: Add EFI variable store option support

[Benjamin Doron (Code Review)]

Attention is currently required from: Martin L Roth, Patrick Rudolph, Jakub Czapiga, Matt DeVillier, Angel Pons, Arthur Heymans, Martin Roth, David Milosevic.

Benjamin Doron has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/52564 )

Change subject: drivers/efi: Add EFI variable store option support
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Patch Set 23:

(1 comment)

File src/drivers/efi/Kconfig:

https://review.coreboot.org/c/coreboot/+/52564/comment/d105619d_c054c8fc 
PS10, Line 1: DRIVERS_EFI_VARIABLE_STORE
> Including multiple UDK could result in conflicts. […]

- Pi/UefiBaseType.h: Includes Base.h, which includes ProcessorBind.h. These aren't too likely to change: they're compiler pragmas, attributes, processor and UEFI-specific defines.
- Pi/UefiMultiPhase.h: Includes Guid/WinCertificate.h. Its contents aren't important here.

It's a bigger issue here if there's no UDK (maybe if another driver includes incorrect headers too). vendorcode/intel/Makefile.inc is a 'if BINDING, elseif BINDING, endif' statement, so we can only use one set.

So, how about some of each: Including these headers directly, and `select UDK_2017_BINDING if !(UEFI_2_4_BINDING || UDK_202005_BINDING || UDK_202111_BINDING)` - it's inefficient and will probably break, but it at least avoids recursive dependencies.

If EDK2 headers will be used more in the codebase, it would be better to pass bindings more specifically to compiler units.