event/sw: fix credit return on invalid queue id

event/sw: fix credit return on invalid queue id

This patch returns a credit when an rte_event is
enqueued with an invalid queue_id. Previously a
credit was leaked from the system.

Note that the eventdev instance does not attempt
to free any resources that the rte_event owns. As
a result, resources owned by the rte_event are leaked.
Eg. if the rte_event represents an rte_mbuf, the mbuf
will not be freed, and causes a leak from the mempool.

Fixes: 656af9180014 ("event/sw: add worker core functions")

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: David Hunt <david.hunt@intel.com>