crypto: tcrypt - Fix potential leak in test_aead_speed() if aad_size is too big

Fix a potential memory leak in the error handling of test_aead_speed(). In case
the size check on the associate data length parameter fails, the function goes
through the wrong exit label. Reported by Coverity - CID 1163870.

Signed-off-by: Christian Engelmayer <cengelma@gmx.at>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>