crypto: ccp - memset structure fields to zero before reuse

commit 20e833dc upstream.

The AES GCM function reuses an 'op' data structure, which members
contain values that must be cleared for each (re)use.

This fix resolves a crypto self-test failure:
alg: aead: gcm-aes-ccp encryption test failed (wrong result) on test vector 2, cfg="two even aligned splits"

Fixes: 36cf515b ("crypto: ccp - Enable support for AES GCM on v5 CCPs")
Cc: <stable@vger.kernel.org>
Signed-off-by: Gary R Hook <gary.hook@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>