arm64: mm: make create_mapping_late() non-allocating

The only purpose served by create_mapping_late() is to remap the already
mapped .text and .rodata kernel segments with read-only permissions. Since
we no longer allow block mappings to be split or merged,
create_mapping_late() should not pass an allocation function pointer into
__create_pgd_mapping(). So pass NULL instead.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laura Abbott <labbott@redhat.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>