crypto: inside-secure - Add support for the ofb(sm4) skcipher

This patch adds support for SM4 in OFB mode, i.e. skcipher ofb(sm4).

changes since v1:
- nothing

Signed-off-by: Pascal van Leeuwen <pvanleeuwen@verimatrix.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>