Fix linux can-utils bus numbering (commaai#637)

Author: vanillagorillaa

drivers/linux/README.md

@@ -17,3 +17,12 @@ usage:
 
 You will need to bring it up using `sudo ifconfig can0 up` or
 `sudo ip link set dev can0 up`, depending on your platform.
+
+Note that you may have to setup udev rules for Linux
+``` bash
+sudo tee /etc/udev/rules.d/11-panda.rules <<EOF
+SUBSYSTEM=="usb", ATTRS{idVendor}=="bbaa", ATTRS{idProduct}=="ddcc", MODE="0666"
+SUBSYSTEM=="usb", ATTRS{idVendor}=="bbaa", ATTRS{idProduct}=="ddee", MODE="0666"
+EOF
+sudo udevadm control --reload-rules && sudo udevadm trigger`
+```

drivers/linux/panda.c

@@ -81,8 +81,8 @@ static const struct usb_device_id panda_usb_table[] = {
 MODULE_DEVICE_TABLE(usb, panda_usb_table);
 
 
-// panda:       CAN1 = 0   CAN2 = 1   CAN3 = 4
-const int can_numbering[] = {0,1,4};
+// panda:       CAN1 = 0   CAN2 = 1   CAN3 = 2
+const int can_numbering[] = {0,1,2};
 
 struct panda_inf_priv *
 panda_get_inf_from_bus_id(struct panda_dev_priv *priv_dev, int bus_id){