UPSTREAM: arm64/efi: remove idmap manipulations from UEFI code

Now that we have moved the call to SetVirtualAddressMap() to the stub,
UEFI has no use for the ID map, so we can drop the code that installs
ID mappings for UEFI memory regions.

Acked-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Tested-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>

(cherry picked from commit 9679be10)
Signed-off-by: Tomasz Figa <tfiga@chromium.org>

Bug: 24475017

Change-Id: I78c5d9d29ba6cee70bd12a44e3ac88a88891ec4b
Signed-off-by: Kees Cook <keescook@google.com>