headers: Fix headers across the project

Any word started with underscore followed by and uppercase letter or a
second underscore is a reserved word according with C99.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

include/mgmt/buf.h

@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#ifndef H_MGMT_BUF
-#define H_MGMT_BUF
+#ifndef ZEPHYR_INCLUDE_MGMT_BUF_H_
+#define ZEPHYR_INCLUDE_MGMT_BUF_H_
 
 #include <inttypes.h>
 #include "cbor_encoder_writer.h"

include/mgmt/serial.h

@@ -56,8 +56,8 @@
  * | Initial Value | 0             |
  */
 
-#ifndef H_MGMT_SERIAL_
-#define H_MGMT_SERIAL_
+#ifndef ZEPHYR_INCLUDE_MGMT_SERIAL_H_
+#define ZEPHYR_INCLUDE_MGMT_SERIAL_H_
 
 #include <zephyr/types.h>
 

include/mgmt/smp.h

@@ -4,8 +4,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#ifndef H_ZEPHYR_SMP_
-#define H_ZEPHYR_SMP_
+#ifndef ZEPHYR_INCLUDE_MGMT_SMP_H_
+#define ZEPHYR_INCLUDE_MGMT_SMP_H_
 
 #ifdef __cplusplus
 extern "C" {

include/mgmt/smp_bt.h

@@ -8,8 +8,8 @@
  * @brief Bluetooth transport for the mcumgr SMP protocol.
  */
 
-#ifndef H_SMP_BT_
-#define H_SMP_BT_
+#ifndef ZEPHYR_INCLUDE_MGMT_SMP_BT_H_
+#define ZEPHYR_INCLUDE_MGMT_SMP_BT_H_
 
 #include <zephyr/types.h>
 struct bt_conn;