test/crypto-perf: support DOCSIS protocol

Update test-crypto-perf app to calculate DOCSIS throughput numbers.

1 new parameter is added for DOCSIS:
--docsis-hdr-sz <n>

./dpdk-test-crypto-perf -l 3,4 --socket-mem 2048,0
--vdev crypto_aesni_mb_pmd_1 -n 1 -- --devtype crypto_aesni_mb
--optype docsis --cipher-algo aes-docsisbpi --cipher-op encrypt
--cipher-key-sz 16 --cipher-iv-sz 16 --burst-sz 32 --total-ops 20000000
--buffer-sz 1024 --silent --docsis-hdr-sz 17

Signed-off-by: David Coyle <david.coyle@intel.com>
Signed-off-by: Mairtin o Loingsigh <mairtin.oloingsigh@intel.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>