The CAN gateway was not implemented as per-net in the initial network
namespace support by Mario Kicherer (8e8cda6d).
This patch enables the CAN gateway to be used in different namespaces.
Signed-off-by: NOliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>