MINOR: kqueue: exclusively rely on the kqueue returned status

MINOR: kqueue: exclusively rely on the kqueue returned status

After commit e852545 ("MEDIUM: polling: centralize polled events processing")
all pollers stopped to explicitly check the FD's polled status, except the
kqueue poller which is constructed a bit differently. It doesn't seem possible
to cause any issue such as missing an event however, but anyway it's better to
definitely get rid of this since the event filter already provides the event
direction.