fbdev/arcfb: Set FBINFO_VIRTFB flag

The arcfb driver operates on 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>
Cc: Jaya Kumar <jayalk@intworks.biz>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231127131655.4020-6-tzimmermann@suse.de

drivers/video/fbdev/arcfb.c

@@ -529,6 +529,7 @@ static int arcfb_probe(struct platform_device *dev)
 	if (!info)
 		goto err_fb_alloc;
 
+	info->flags |= FBINFO_VIRTFB;
 	info->screen_buffer = videomemory;
 	info->fbops = &arcfb_ops;