X.509: Support parsing certificate using SM2 algorithm

The SM2-with-SM3 certificate generated by latest openssl no longer
reuses the OID_id_ecPublicKey, but directly uses OID_sm2. This patch
supports this type of x509 certificate parsing.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>