examples/ipsec-secgw: support event Rx adapter

examples/ipsec-secgw: support event Rx adapter

Add Rx adapter support. The event helper init routine will initialize
the Rx adapter according to the configuration. If Rx adapter config
is not present it will generate a default config. If there are enough
event queues available it will map eth ports and event queues 1:1
(one eth port will be connected to one event queue). Otherwise it
will map all eth ports to one event queue.

Signed-off-by: Anoob Joseph <anoobj@marvell.com>
Signed-off-by: Lukasz Bartosik <lbartosik@marvell.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>