Use #if defined TARGET_STM32L4

Author: pmancele

targets/TARGET_STM/gpio_api.c

@@ -73,7 +73,7 @@ GPIO_TypeDef *Set_GPIO_Clock(uint32_t port_idx) {
 #endif
 #if defined GPIOG_BASE
         case PortG:
-#if defined STM32L4
+#if defined TARGET_STM32L4
             __HAL_RCC_PWR_CLK_ENABLE();
             HAL_PWREx_EnableVddIO2();
 #endif