arm64: Add tlbi_user_level TLB invalidation helper

Add a level-hinted parameter to __tlbi_user, which only gets used
if ARMv8.4-TTL gets detected.

ARMv8.4-TTL provides the TTL field in tlbi instruction to indicate
the level of translation table walk holding the leaf entry for the
address that is being invalidated.

This patch set the default level value of flush_tlb_range() to 0,
which will be updated in future patches.  And set the ttl value of
flush_tlb_page_nosync() to 3 because it is only called to flush a
single pte page.

Signed-off-by: Zhenyu Ye <yezhenyu2@huawei.com>
Link: https://lore.kernel.org/r/20200625080314.230-4-yezhenyu2@huawei.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>