Use local IV storage in e_sm4.c

Inline the pre-13273237a65d46186b6bea0b51aec90670d4598a versions
of EVP_CIPHER_CTX_iv(), EVP_CIPHER_CTX_original_iv(), and
EVP_CIPHER_CTX_iv_noconst() in e_sm4.c.

For the legacy implementations, there's no need to use an
in-provider storage for the IV, when the crypto operations
themselves will be performed outside of the provider.

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/12233)
