This patch adds AES-NI/AVX/x86_64 assembler implementation of SM4
block cipher. Through two affine transforms, we can use the AES S-Box
to simulate the SM4 S-Box to achieve the effect of instruction
acceleration.

The main algorithm implementation comes from SM4 AES-NI work by
libgcrypt and Markku-Juhani O. Saarinen at:
https://github.com/mjosaarinen/sm4ni

This optimization supports the four modes of SM4, ECB, CBC, CFB, and
CTR. Since CBC and CFB do not support multiple block parallel
encryption, the optimization effect is not obvious.

Benchmark on Intel Xeon Cascadelake, the data comes from the 218 mode
and 518 mode of tcrypt. The abscissas are blocks of different lengths.
The data is tabulated and the unit is Mb/s:

sm4-generic   |    16      64     128     256    1024    1420    4096
      ECB enc | 40.99   46.50   48.05   48.41   49.20   49.25   49.28
      ECB dec | 41.07   46.99   48.15   48.67   49.20   49.25   49.29
      CBC enc | 37.71   45.28   46.77   47.60   48.32   48.37   48.40
      CBC dec | 36.48   44.82   46.43   47.45   48.23   48.30   48.36
      CFB enc | 37.94   44.84   46.12   46.94   47.57   47.46   47.68
      CFB dec | 37.50   42.84   43.74   44.37   44.85   44.80   44.96
      CTR enc | 39.20   45.63   46.75   47.49   48.09   47.85   48.08
      CTR dec | 39.64   45.70   46.72   47.47   47.98   47.88   48.06
sm4-aesni-avx
      ECB enc | 33.75  134.47  221.64  243.43  264.05  251.58  258.13
      ECB dec | 34.02  134.92  223.11  245.14  264.12  251.04  258.33
      CBC enc | 38.85   46.18   47.67   48.34   49.00   48.96   49.14
      CBC dec | 33.54  131.29  223.88  245.27  265.50  252.41  263.78
      CFB enc | 38.70   46.10   47.58   48.29   49.01   48.94   49.19
      CFB dec | 32.79  128.40  223.23  244.87  265.77  253.31  262.79
      CTR enc | 32.58  122.23  220.29  241.16  259.57  248.32  256.69
      CTR dec | 32.81  122.47  218.99  241.54  258.42  248.58  256.61
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>