can: dev: move netlink related code into seperate file

This patch moves the netlink related code of the CAN device infrastructure into
a separate file.
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-7-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/dev/Makefile

@@ -4,6 +4,7 @@ obj-$(CONFIG_CAN_DEV)		+= can-dev.o
 can-dev-y			+= bittiming.o
 can-dev-y			+= dev.o
 can-dev-y			+= length.o
+can-dev-y			+= netlink.o
 can-dev-y			+= rx-offload.o
 can-dev-y                       += skb.o
 

include/linux/can/dev.h

@@ -100,6 +100,8 @@ static inline void can_set_static_ctrlmode(struct net_device *dev,
 		dev->mtu = CANFD_MTU;
 }
 
+void can_setup(struct net_device *dev);
+
 struct net_device *alloc_candev_mqs(int sizeof_priv, unsigned int echo_skb_max,
 				    unsigned int txqs, unsigned int rxqs);
 #define alloc_candev(sizeof_priv, echo_skb_max) \
@@ -130,4 +132,8 @@ void of_can_transceiver(struct net_device *dev);
 static inline void of_can_transceiver(struct net_device *dev) { }
 #endif
 
+extern struct rtnl_link_ops can_link_ops;
+int can_netlink_register(void);
+void can_netlink_unregister(void);
+
 #endif /* !_CAN_DEV_H */