Add support for canbus activity led indicators on usb_8dev devices by
calling appropriate can_led functions.

These are only enabled when CONFIG_CAN_LEDS is Y, becomes no-op
otherwise.
Signed-off-by: NBernd Krumboeck <krumboeck@universalnet.at>
Signed-off-by: NFabio Baltieri <fabio.baltieri@gmail.com>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>