ACPI: video: fix build for CONFIG_ACPI=n

In file included from drivers/gpu/drm/i915/intel_opregion.c:30:
include/acpi/video.h:22: warning: ‘struct acpi_device’ declared inside parameter list
...
include/acpi/video.h:24: error: ‘ENODEV’ undeclared (first use in this function)
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Len Brown <len.brown@intel.com>

include/acpi/video.h

 #ifndef __ACPI_VIDEO_H
 #define __ACPI_VIDEO_H
 
+#include <linux/errno.h> /* for ENODEV */
+
+struct acpi_device;
+
 #define ACPI_VIDEO_DISPLAY_CRT  1
 #define ACPI_VIDEO_DISPLAY_TV   2
 #define ACPI_VIDEO_DISPLAY_DVI  3
@@ -26,4 +30,3 @@ static inline int acpi_video_get_edid(struct acpi_device *device, int type,
 #endif
 
 #endif
-