drm: set the type of the drm_framebuffer::fbdev field

The fbdev field of the drm_framebuffer structure is always used to store
a pointer to a fb_info, so there is no reason for it to be void*.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Dave Airlie <airlied@redhat.com>

include/drm/drm_crtc.h

@@ -256,7 +256,7 @@ struct drm_framebuffer {
 	unsigned int depth;
 	int bits_per_pixel;
 	int flags;
-	void *fbdev;
+	struct fb_info *fbdev;
 	u32 pseudo_palette[17];
 	struct list_head filp_head;
 	/* if you are using the helper */