Move can_helper.h into hal/ given its a requirement of the can c hal.

hal/can_helper.h

@@ -0,0 +1,53 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#ifndef MBED_CAN_HELPER_H
+#define MBED_CAN_HELPER_H
+
+#if DEVICE_CAN
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum CANFormat {
+    CANStandard = 0,
+    CANExtended = 1,
+    CANAny = 2
+};
+typedef enum CANFormat CANFormat;
+
+enum CANType {
+    CANData   = 0,
+    CANRemote = 1
+};
+typedef enum CANType CANType;
+
+struct CAN_Message {
+    unsigned int   id;                 // 29 bit identifier
+    unsigned char  data[8];            // Data field
+    unsigned char  len;                // Length of data field in bytes
+    CANFormat      format;             // 0 - STANDARD, 1- EXTENDED IDENTIFIER
+    CANType        type;               // 0 - DATA FRAME, 1 - REMOTE FRAME
+};
+typedef struct CAN_Message CAN_Message;
+
+#ifdef __cplusplus
+};
+#endif
+
+#endif
+
+#endif // MBED_CAN_HELPER_H