eventdev/eth_rx: add event buffer size configurability

eventdev/eth_rx: add event buffer size configurability

Currently event buffer is static array with a default size defined
internally.

To configure event buffer size from application,
rte_event_eth_rx_adapter_create_with_params() API is added which
takes struct rte_event_eth_rx_adapter_params to configure event
buffer size in addition other params. The event buffer size is
rounded up for better buffer utilization and performance. In case
of NULL params argument, default event buffer size is used.

Signed-off-by: Naga Harish K S V <s.v.naga.harish.k@intel.com>
Signed-off-by: Ganapati Kundapura <ganapati.kundapura@intel.com>
Acked-by: Jay Jayatheerthan <jay.jayatheerthan@intel.com>
Acked-by: Jerin Jacob <jerinj@marvell.com>