crypto: ccp - Fix oops by properly managing allocated structures

A plaintext or ciphertext length of 0 is allowed in AES, in which case
no encryption occurs. Ensure that we don't clean up data structures
that were never allocated.

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>