fbdev/au1200fb: Set FBINFO_VIRTFB flag

The au1200fb driver operates on DMA-able system memory. Mark the
framebuffer accordingly. Helpers operating on the framebuffer memory
will test for the presence of this flag.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231127131655.4020-17-tzimmermann@suse.de

drivers/video/fbdev/au1200fb.c

@@ -1568,6 +1568,8 @@ static int au1200fb_init_fbinfo(struct au1200fb_device *fbdev)
 	fbi->fix.mmio_len = 0;
 	fbi->fix.accel = FB_ACCEL_NONE;
 
+	fbi->flags |= FBINFO_VIRTFB;
+
 	fbi->screen_buffer = fbdev->fb_mem;
 
 	au1200fb_update_fbinfo(fbi);