eventdev: add usage hints to port configure API

eventdev: add usage hints to port configure API

This commit introduces 3 flags to the port configuration flags.
These flags allow the application to indicate what type of work
is expected to be performed by an eventdev port.

The three new flags are
- RTE_EVENT_PORT_CFG_HINT_PRODUCER (mostly RTE_EVENT_OP_NEW events)
- RTE_EVENT_PORT_CFG_HINT_CONSUMER (mostly RTE_EVENT_OP_RELEASE events)
- RTE_EVENT_PORT_CFG_HINT_WORKER   (mostly RTE_EVENT_OP_FORWARD events)

These flags are only hints, and the PMDs must operate under the
assumption that any port can enqueue an event with any type of op.

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>