crypto: sm2 - make dependent on sm3 library

SM3 generic library is stand-alone implementation, it is necessary
for the calculation of sm2 z digest to depends on SM3 library
instead of sm3-generic.

Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>