Fix compiler warning: unused parameter [-Wunused-parameter]

Fix #44

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

Author: fpistm

cores/arduino/stm32/analog.c

@@ -255,6 +255,8 @@ void HAL_DAC_MspInit(DAC_HandleTypeDef *hdac)
 {
   GPIO_InitTypeDef          GPIO_InitStruct;
   GPIO_TypeDef *port;
+  UNUSED(hdac);
+
   /*##-1- Enable peripherals and GPIO Clocks #################################*/
   /* Enable GPIO clock ****************************************/
   port = set_GPIO_Port_Clock(STM_PORT(g_current_pin));
@@ -338,6 +340,7 @@ void dac_write_value(PinName pin, uint32_t value, uint8_t do_init)
   */
 void HAL_DAC_MspDeInit(DAC_HandleTypeDef* hdac)
 {
+  UNUSED(hdac);
   /* DAC Periph clock disable */
 #ifdef __HAL_RCC_DAC1_CLK_DISABLE
   __HAL_RCC_DAC1_CLK_DISABLE();

cores/arduino/stm32/interrupt.c

@@ -206,6 +206,7 @@ void stm32_interrupt_enable(GPIO_TypeDef *port, uint16_t pin, void (*callback)(v
   */
 void stm32_interrupt_disable(GPIO_TypeDef *port, uint16_t pin)
 {
+  UNUSED(port);
   uint8_t id = get_pin_id(pin);
   gpio_irq_conf[id].callback = NULL;
 

cores/arduino/stm32/uart_emul.c

@@ -131,7 +131,7 @@ uint8_t g_rx_data[1];
 /** @addtogroup STM32F4xx_System_Private_FunctionPrototypes
   * @{
   */
-static void uart_emul_timer_irq(stimer_t *obj) {g_uartEmul_config[UART1_EMUL_E].uart_rx_irqHandle();}
+static void uart_emul_timer_irq(stimer_t *obj) {UNUSED(obj); g_uartEmul_config[UART1_EMUL_E].uart_rx_irqHandle();}
 
 /**
   * @}
@@ -152,6 +152,7 @@ void HAL_UART_Emul_MspInit(UART_Emul_HandleTypeDef *huart)
   GPIO_InitTypeDef          GPIO_InitStruct;
   GPIO_TypeDef *port_rx;
   GPIO_TypeDef *port_tx;
+  UNUSED(huart);
 
   // Enable GPIO clock
   port_rx = set_GPIO_Port_Clock(STM_PORT(g_uartEmul_config[UART1_EMUL_E].pin_rx));
@@ -189,6 +190,7 @@ void HAL_UART_Emul_MspDeInit(UART_Emul_HandleTypeDef *huart)
 {
   GPIO_TypeDef *port_rx = get_GPIO_Port(STM_PORT(g_uartEmul_config[UART1_EMUL_E].pin_rx));
   GPIO_TypeDef *port_tx = get_GPIO_Port(STM_PORT(g_uartEmul_config[UART1_EMUL_E].pin_tx));
+  UNUSED(huart);
 
   __UART_EMUL_CLK_DISABLE();