app/crypto-perf: fix invalid latency for QAT

app/crypto-perf: fix invalid latency for QAT

Fixes invalid latency result when using the performance application and
hardware QAT PMD. It occurred when the number of processed packets was
higher then the size of the internal QAT PMD ring buffer and the buffer
was overflowed.
Fixed by correcting the registration of the enqueued packets and freeing
memory space for not enqueued packets.

Fixes: f8be1786b1b8 ("app/crypto-perf: introduce performance test application")

Signed-off-by: Slawomir Mrozowicz <slawomirx.mrozowicz@intel.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>