HiSilicon Taishan v110 CPUs didn't implement CSV2 field of the
ID_AA64PFR0_EL1, but spectre-v2 is mitigated by hardware, so
whitelist the MIDR in the safe list.

Signed-off-by: Wei Li <liwei391@huawei.com>
[hanjun: re-write the commit log]
Signed-off-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>