arm64: extable: move _cond_extable to _cond_uaccess_extable

arm64: extable: move _cond_extable to _cond_uaccess_extable

Currently, We use _cond_extable for cache maintenance uaccess helper
caches_clean_inval_user_pou(), so this should be moved over to
EX_TYPE_UACCESS_ERR_ZERO and rename _cond_extable to _cond_uaccess_extable
for clarity.

Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Tong Tiangen <tongtiangen@huawei.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220621072638.1273594-6-tongtiangen@huawei.com
Signed-off-by: Will Deacon <will@kernel.org>