efi/x86: Split SetVirtualAddresMap() wrappers into 32 and 64 bit versions

Split the phys_efi_set_virtual_address_map() routine into 32 and 64 bit
versions, so we can simplify them individually in subsequent patches.

There is very little overlap between the logic anyway, and this has
already been factored out in prolog/epilog routines which are completely
different between 32 bit and 64 bit. So let's take it one step further,
and get rid of the overlap completely.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Matthew Garrett <mjg59@google.com>
Cc: linux-efi@vger.kernel.org
Link: https://lkml.kernel.org/r/20200103113953.9571-8-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>