[components][drivers][can] can.c fix bug.

components/drivers/can/can.c

@@ -53,7 +53,7 @@ rt_inline int _can_int_rx(struct rt_can_device *can, struct rt_can_msg *data, in
     {
         rt_base_t level;
 #ifdef RT_CAN_USING_HDR
-        rt_int32_t hdr;
+        rt_int8_t hdr;
 #endif /*RT_CAN_USING_HDR*/
         struct rt_can_msg_list *listmsg = RT_NULL;
 
@@ -760,7 +760,7 @@ void rt_hw_can_isr(struct rt_can_device *can, int event)
         struct rt_can_rx_fifo *rx_fifo;
         struct rt_can_msg_list *listmsg = RT_NULL;
 #ifdef RT_CAN_USING_HDR
-        rt_int32_t hdr;
+        rt_int8_t hdr;
 #endif
         int ch = -1;
         rt_base_t level;