[PATCH] Introduce OSCCA SM2 asymmetric cipher algorithm

[Tianjia Zhang]

Hello,

This new module implement the SM2 public key algorithm. It was
published by State Encryption Management Bureau, China.
List of specifications for SM2 elliptic curve public key cryptography:

* GM/T 0003.1-2012
* GM/T 0003.2-2012
* GM/T 0003.3-2012
* GM/T 0003.4-2012
* GM/T 0003.5-2012

IETF: https://tools.ietf.org/html/draft-shen-sm2-ecdsa-02
oscca: http://www.oscca.gov.cn/sca/xxgk/2010-12/17/content_1002386.shtml
scctc: http://www.gmbz.org.cn/main/bzlb.html

The sm2 algorithm is based on libgcrypt's mpi implementation, and has
made some additions to the kernel's original mpi library, and added the
implementation of ec to better support elliptic curve-like algorithms.

sm2 has good support in both openssl and gnupg projects, and sm3 and sm4
of the OSCCA algorithm family have also been implemented in the kernel.

Signed-off-by: Tianjia Zhang <tianjia.zhang@xxxxxxxxxxxxxxxxx>

Thanks,
Tianjia