Phonet: disable network namespace support

Phonet: disable network namespace support

[Solved differently upstream]

Network namespace in the Phonet socket stack causes an OOPS when a
namespace is destroyed. This occurs as the loopback exit_net handler is
called after the Phonet exit_net handler, and re-enters the Phonet
stack. I cannot think of any nice way to fix this in kernel <= 2.6.32.

For lack of a better solution, disable namespace support completely.
If you need that, upgrade to a newer kernel.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Ben Hutchings <ben@decadent.org.uk>
Acked-by: David S. Miller <davem@davemloft.net>