soft_decrypt
rv = soft_decrypt(session_p, pEncryptedData, ulEncryptedDataLen,
rv = soft_decrypt(session_p, pWrappedKey, ulWrappedKeyLen, NULL,
rv = soft_decrypt(session_p, pWrappedKey, ulWrappedKeyLen, plain_data,
CK_RV soft_decrypt(soft_session_t *, CK_BYTE_PTR, CK_ULONG, CK_BYTE_PTR,