crypto/scheduler: use proper API for device start/stop

crypto/scheduler: use proper API for device start/stop

The worker PMDs were using direct device start/stop
functions rather than rte_cryptodev_start(),
so rte_crypto_fp_ops never get set. This patch calls
the rte_cryptodev_start and stop APIs which start and
stop devices properly and fp_ops get set.

Reported-by: Ciara Power <ciara.power@intel.com>
Signed-off-by: Akhil Goyal <gakhil@marvell.com>
Acked-by: Fan Zhang <roy.fan.zhang@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>