caif: Bugfix - Poll can't return POLLHUP while connecting.

Discovered bug when testing async connect.
While connecting poll should not return POLLHUP,
but POLLOUT when connected.
Also fixed the sysfs flow-control-counters.

Signed-off-by: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>