efi/x86: Drop two near identical versions of efi_runtime_init()

The routines efi_runtime_init32() and efi_runtime_init64() are
almost indistinguishable, and the only relevant difference is
the offset in the runtime struct from where to obtain the physical
address of the SetVirtualAddressMap() routine.

However, this address is only used once, when installing the virtual
address map that the OS will use to invoke EFI runtime services, and
at the time of the call, we will necessarily be running with a 1:1
mapping, and so there is no need to do the map/unmap dance here to
retrieve the address. In fact, in the preceding changes to these users,
we stopped using the address recorded here entirely.

So let's just get rid of all this code since it no longer serves a
purpose. While at it, tweak the logic so that we handle unsupported
and disable EFI runtime services in the same way, and unmap the EFI
memory map in both cases.

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/20200103113953.9571-12-ardb@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>