revert param default and update docs

Author: dakejahl

docs/en/dronecan/index.md

@@ -270,7 +270,7 @@ PX4 DroneCAN parameters:
 
 [DroneCAN ESCs and servos](../dronecan/escs.md) require the [motor order and servo outputs](../config/actuators.md) to be configured.
 
-Select the CAN interface you want to output the ESC data on. By default CAN2 is selected. [UAVCAN_ESC_IFACE](../advanced_config/parameter_reference.md#UAVCAN_ESC_IFACE)
+Select the CAN interface for ESC data output. All interfaces are selected by default. Avoid using the same interface as other nodes, as ESC messages can saturate the bus and starve other nodes of bandwidth. [UAVCAN_ESC_IFACE](../advanced_config/parameter_reference.md#UAVCAN_ESC_IFACE)
 
 ## QGC CANNODE Parameter Configuration
 

src/drivers/uavcan/module.yaml

@@ -20,7 +20,7 @@ parameters:
         5: CAN6
         6: CAN7
         7: CAN8
-      default: 2
+      default: 255
       min: 1
       max: 255
       reboot_required: true