tipc: eliminate redundant locking

The three functions tipc_portimportance(), tipc_portunreliable() and
tipc_portunreturnable() and their corresponding tipc_set* functions,
are all grabbing port_lock when accessing the targeted port. This is
unnecessary in the current code, since these calls only are made from
within socket downcalls, already protected by sock_lock.

We remove the redundant locking. Also, since the functions now become
trivial one-liners, we move them to port.h and make them inline.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Reviewed-by: Ying Xue <ying.xue@windriver.com>
Reviewed-by: Erik Hugne <erik.hugne@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>