drm/atmel-hlcdc: add missing headers

Signed-off-by: Ludovic Desroches <ludovic.desroches@microchip.com>

Author: ldesroches

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h

@@ -13,6 +13,9 @@
 
 #include <linux/regmap.h>
 
+#include <drm/drm_crtc.h>
+#include <drm/drm_encoder.h>
+#include <drm/drm_modes.h>
 #include <drm/drm_plane.h>
 
 #define ATMEL_HLCDC_LAYER_CHER			0x0