event/octeontx: fix SSO fast path

event/octeontx: fix SSO fast path

Segmentation fault is observed as soon as any  application
with ethdev event is launched as ev->mbuf was not set properly.

Fixing sub event type violation as in OCTEONTX event device
sub_event_type is used to store the ethernet port identifier
when work is received from OCTEONTX ethernet device. This violates
the event device spec as sub_event_type should be 0 in the initial
receive stage. Setting sub_event_type to 0 after copying the port id
in single workslot mode.

Fixes: 44a2cebbd489 ("crypto/octeontx: add crypto adapter data path")
Cc: stable@dpdk.org
Signed-off-by: Harman Kalra <hkalra@marvell.com>
Signed-off-by: Pavan Nikhilesh <pbhagavatula@marvell.com>