canbus: Call can_notify_rx() at startup so low-level code does not need to

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/generic/canbus.c

@@ -213,6 +213,7 @@ void
 canbus_set_uuid(void *uuid)
 {
     memcpy(canbus_uuid, uuid, sizeof(canbus_uuid));
+    canbus_notify_rx();
 
     // Send initial message
     can_process_uuid(0, 0, NULL);

src/stm32/can.c

@@ -290,9 +290,6 @@ can_init(void)
     canbus_set_filter(CANBUS_ID_SET);
 
     /*##-3- Configure Interrupts #################################*/
-
-    SOC_CAN->IER = CAN_IER_FMPIE0; // RX mailbox IRQ
-
     armcm_enable_irq(CAN_IRQHandler, CAN_RX0_IRQn, 0);
     if (CAN_RX0_IRQn != CAN_RX1_IRQn)
         armcm_enable_irq(CAN_IRQHandler, CAN_RX1_IRQn, 0);