arm64: mm: Add is_el1_data_abort() helper

We alread have is_el1_instruction_abort(), add is_el1_data_abort()
helper and use it.

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210603120239.169018-1-wangkefeng.wang@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>