drm/rockchip: dw_hdmi: remove unused #include

drm_encoder_slave is not used in this file.
Signed-off-by: NJohn Keeping <john@metanate.com>

drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c

@@ -15,7 +15,6 @@
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_edid.h>
-#include <drm/drm_encoder_slave.h>
 #include <drm/bridge/dw_hdmi.h>
 
 #include "rockchip_drm_drv.h"