hsr: set .netnsok flag

hsr: set .netnsok flag

The hsr module has been supporting the list and status command.
(HSR_C_GET_NODE_LIST and HSR_C_GET_NODE_STATUS)
These commands send node information to the user-space via generic netlink.
But, in the non-init_net namespace, these commands are not allowed
because .netnsok flag is false.
So, there is no way to get node information in the non-init_net namespace.

Fixes: f421436a591d ("net/hsr: Add support for the High-availability Seamless Redundancy protocol (HSRv0)")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>