sched: act: count in the size of action flags bitfield

The put of the flags was added by the commit referenced in fixes tag,
however the size of the message was not extended accordingly.

Fix this by adding size of the flags bitfield to the message size.

Fixes: e3822678 ("net: sched: update action implementations to support flags")
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>