drivers: can: mcan: fix handling of bus-off status events

Fix handling bus-off events in the Bosch M_CAN driver backend:
- Cancel all pending TX buffers when entering bus-off state
- Call all pending TX buffer callbacks with -ENETUNREACH when entering
  bus-off
- Automatically initiate bus-off recovery if
  CONFIG_CAN_AUTO_BUS_OFF_RECOVERY=y

Fixes: #68953

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>