examples/l2fwd-crypto: use cryptodev algorithm parser

examples/l2fwd-crypto: use cryptodev algorithm parser

L2fwd-crypto app was creating an array of strings for the
supported algorithms, which was different from the strings
that are now in cryptodev.

Use the new API in cryptodev to parse the string from the user,
to get the algorithm enum, instead, so it is not necessary to add
a new supported algorithm in the cryptodev library and this app.

Signed-off-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>
Acked-by: Fiona Trahe <fiona.trahe@intel.com>
Acked-by: Hemant Agrawal <hemant.agrawal@nxp.com>