RN42 driver: small cleanups (#18310)

* RN42 driver: small cleanups

* Include header

* Fix mouse report per RN42 UG

* Spacing for consistency

drivers/bluetooth/rn42.h

@@ -14,6 +14,8 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include <stdint.h>
+
 #include "report.h"
 
 void rn42_init(void);
@@ -22,4 +24,4 @@ void rn42_send_keyboard(report_keyboard_t *report);
 
 void rn42_send_mouse(report_mouse_t *report);
 
-void rn42_send_consumer(uint16_t data);
+void rn42_send_consumer(uint16_t usage);