drm/nouveau/backlight: remove dependence on nouveau_drv.h

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_encoder.h

@@ -27,8 +27,9 @@
 #ifndef __NOUVEAU_ENCODER_H__
 #define __NOUVEAU_ENCODER_H__
 
+#include <subdev/bios/dcb.h>
+
 #include "drm_encoder_slave.h"
-#include "nouveau_drv.h"
 #include "nv04_display.h"
 
 #define NV_DPMS_CLEARED 0x80