crypto: inside-secure - Fix build error with CONFIG_CRYPTO_SM3=m

Always take the zero length hash value for SM3 from the local constant
to avoid a reported build error when SM3 is configured to be a module.

Fixes: 0f2bc131 ("crypto: inside-secure - Added support for...")
Signed-off-by: Pascal van Leeuwen <pvanleeuwen@verimatrix.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>