examples/eventdev: support Rx adapter

Use event Rx adapter for packets Rx instead of explicit producer logic.
Use service run iter function for granular control instead of using
dedicated service lcore.

Signed-off-by: Pavan Nikhilesh <pbhagavatula@caviumnetworks.com>
Acked-by: Harry van Haaren <harry.van.haaren@intel.com>