event/octeontx2: fix sub event type

event/octeontx2: fix sub event type

In OCTEONTX2 event device we use sub_event_type to store the ethernet
port identifier when we receive work from OCTEONTX2 ethernet device.
This violates the event device spec as sub_event_type should be 0 in
the initial receive stage.
Set sub_event_type to 0 after copying the port id.

Fixes: 0fe4accd8ec8 ("event/octeontx2: add Rx adapter fastpath ops")
Cc: stable@dpdk.org
Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>