Cleanup and refactoring of the STM32w port

This is a general cleanup of things like code style issues and code structure of the STM32w port to make it more like the rest of Contiki is structured.

cpu/stm32w108/dev/stm32w-radio.h

@@ -1,3 +1,9 @@
+/**
+ * \addtogroup stm32w-cpu
+ *
+ * @{
+ */
+
 /*
  * Copyright (c) 2007, Swedish Institute of Computer Science.
  * All rights reserved.
@@ -26,8 +32,6 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * This file is part of the Contiki operating system.
- *
  */
 
 /**
@@ -45,14 +49,15 @@
 #include "hal/hal.h"
 #include "simplemac/include/phy-library.h"
 
-int stm32w_radio_set_channel(uint8_t channel);
-short last_packet_rssi();
-
 #define STM32W_MAX_PACKET_LEN      127
 
 extern const struct radio_driver stm32w_radio_driver;
 
+int stm32w_radio_set_channel(uint8_t channel);
+
+short last_packet_rssi();
+
 int stm32w_radio_is_on(void);
 
-
 #endif /* __STM32W_H__ */
+/** @} */