eventdev: ease single-link queue config requirements

eventdev: ease single-link queue config requirements

Events sent through single-link queues are naturally in-order and
atomic, without reordering or atomic scheduling. Logically the
nb_atomic_flows and nb_atomic_order_sequences arguments don't apply to a
single link queue, but applications must set these (depending on the queue
config type) to bypass the is_valid_{ordered, atomic}_queue_conf() checks
in the eventdev layer.

This commit updates those is_valid_* functions to ignore queues with the
SINGLE_LINK flag, to simplify their configuration.

Signed-off-by: Gage Eads <gage.eads@intel.com>
Acked-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>