app/crypto-perf: support multiple queue pairs

Add support for multiple queue pairs, when there are
more logical cores available than crypto devices enabled.
For instance, if there are 4 cores available and
2 crypto devices, each device will have two queue pairs.

This is useful to have multiple logical cores using
a single crypto device, without needing to initialize
a crypto device per core.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>