can: af_can: fix NULL pointer dereference in can_rcv_filter

In the Linux kernel, the following vulnerability has been resolved:

can: af_can: fix NULL pointer dereference in can_rcv_filter

Analogue to commit 8aa59e355949 ("can: af_can: fix NULL pointer

dereference in can_rx_register()") we need to check for a missing

initialization of ml_priv in the receive path of CAN frames.

Since commit 4e096a18867a ("net: introduce CAN specific pointer in the

struct net_device") the check for dev->type to be ARPHRD_CAN is not

sufficient anymore since bonding or tun netdevices claim to be CAN

devices but do not initialize ml_priv accordingly.