cryptodev: update symmetric session structure

cryptodev: update symmetric session structure

This patch updates the rte_cryptodev_sym_session structure for
cryptodev library. The updates include a changed session private
data array and an added nb_drivers field. They are used to
calculate the correct session header size and ensure safe access
of the session private data.

Signed-off-by: Fan Zhang <roy.fan.zhang@intel.com>
Acked-by: Fiona Trahe <fiona.trahe@intel.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>