clean unuseful comments

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>

Author: fpistm

cores/arduino/stm32/clock.c

@@ -35,67 +35,12 @@
   *
   ******************************************************************************
   */
-/** @addtogroup CMSIS
-  * @{
-  */
-
-/** @addtogroup stm32f4xx_system
-  * @{
-  */
-
-/** @addtogroup STM32F4xx_System_Private_Includes
-  * @{
-  */
 #include "stm32_def.h"
 
 #ifdef __cplusplus
  extern "C" {
 #endif
 
-/**
-  * @}
-  */
-
-/** @addtogroup STM32F4xx_System_Private_TypesDefinitions
-  * @{
-  */
-
-/**
-  * @}
-  */
-
-/** @addtogroup STM32F4xx_System_Private_Defines
-  * @{
-  */
-
-/**
-  * @}
-  */
-
-/** @addtogroup STM32F4xx_System_Private_Macros
-  * @{
-  */
-
-/**
-  * @}
-  */
-
-/** @addtogroup STM32F4xx_System_Private_Variables
-  * @{
-  */
-
-/**
-  * @}
-  */
-
-/** @addtogroup STM32F4xx_System_Private_FunctionPrototypes
-  * @{
-  */
-
-/**
-  * @}
-  */
-
 /**
   * @brief  Function called to read the current micro second
   * @param  None
@@ -176,17 +121,6 @@ void delayInsideIT(uint32_t delay_us)
 #endif
 }
 
-/**
-  * @}
-  */
-
-/**
-  * @}
-  */
-
-/**
-  * @}
-  */
 #ifdef __cplusplus
 }
 #endif