event: fix ring init failure handling

event: fix ring init failure handling

This commit fixes a bug in a 32-bit environment where the
generic ring_init() would fail, but given the interaction
with memzones the next iteration of the event_ring_autotest
would actually *pass* because the ring in question would
exist already an be looked-up.

This commit rightly error checks the result of ring_init(),
and calls rte_free() on the memory as required.

Fixes: dc39e2f359b5 ("eventdev: add ring structure for events")
Cc: stable@dpdk.org
Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>