发送数据前先poll tx尽量清空发送buffer

Signed-off-by: huhui <huhui@sharkgulf.com>

Applications/bsp/can.c

@@ -138,6 +138,7 @@ static void shark_can0_config(void)
 
 
 static int shark_send_can0_data(can_trasnmit_message_struct *P_message){
+	can_tx_poll();
 	if (circle_put_data(&g_tx_circle, (u8 *)P_message, sizeof(can_trasnmit_message_struct))){
 		return CAN_SEND_OK;
 	}