app/crypto-perf: fix IV allocation for AEAD

Memory is reserved after each crypto operation
for the necessary IV(s), which could be for cipher,
authentication or AEAD algorithms.
However, for AEAD algorithms (such as AES-GCM), this
memory was not being reserved, leading to potential
memory overflow.

Fixes: 8a5b494a7f99 ("app/test-crypto-perf: add AEAD parameters")

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>