UPSTREAM: arm64/efi: split off EFI init and runtime code for reuse by 32-bit ARM

UPSTREAM: arm64/efi: split off EFI init and runtime code for reuse by 32-bit ARM

This splits off the early EFI init and runtime code that
- discovers the EFI params and the memory map from the FDT, and installs
  the memblocks and config tables.
- prepares and installs the EFI page tables so that UEFI Runtime Services
  can be invoked at the virtual address installed by the stub.

This will allow it to be reused for 32-bit ARM.

Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Change-Id: I143e4b38a5426f70027eff6cc5f732ac370ae69d
(cherry picked from commit e5bc22a42e4d46cc203fdfb6d2c76202b08666a0)
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>