[HAL][LTDC] Update to avoid compilation errors when the DSI module isn't enabled

Inc/stm32f4xx_hal_ltdc_ex.h

diff --git a/Inc/stm32f4xx_hal_ltdc_ex.h b/Inc/stm32f4xx_hal_ltdc_ex.h
index b9c39e4..a981727 100644
--- a/Inc/stm32f4xx_hal_ltdc_ex.h
+++ b/Inc/stm32f4xx_hal_ltdc_ex.h
@@ -27,6 +27,8 @@
 /* Includes ------------------------------------------------------------------*/
 #include "stm32f4xx_hal_def.h"
 
+#if defined(HAL_LTDC_MODULE_ENABLED) && defined(HAL_DSI_MODULE_ENABLED)
+
 #if defined (LTDC) && defined (DSI)
 
 #include "stm32f4xx_hal_dsi.h"
@@ -76,6 +78,8 @@
 
 #endif /* LTDC && DSI */
 
+#endif /* HAL_LTCD_MODULE_ENABLED && HAL_DSI_MODULE_ENABLED */
+
 #ifdef __cplusplus
 }
 #endif