rocker: mark STP update as 'no wait' processing

We can get STP updates from the bridge driver in atomic and non-atomic
contexts.  Since we can't test what context we're getting called in,
do the STP processing as 'no wait', which will cover all cases.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>