Avoid divide-by-zero in kmac_prov.c's bytepad()

Avoid divide-by-zero in kmac_prov.c's bytepad()

This would happen if EVP_MD_get_block_size() returned 0
so we return an error instead.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21698)