xen: drop writing error messages to xenstore

xenbus_va_dev_error() will try to write error messages to Xenstore
under the error/<dev-name>/error node (with <dev-name> something like
"device/vbd/51872"). This will fail normally and another message
about this failure is added to dmesg.

I believe this is a remnant from very ancient times, as it was added
in the first pvops rush of commits in 2007.

So remove the additional message when writing to Xenstore failed as
a minimum step.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracel.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

drivers/xen/xenbus/xenbus_client.c

@@ -278,10 +278,8 @@ static void xenbus_va_dev_error(struct xenbus_device *dev, int err,
 	dev_err(&dev->dev, "%s\n", printf_buffer);
 
 	path_buffer = kasprintf(GFP_KERNEL, "error/%s", dev->nodename);
-	if (!path_buffer ||
-	    xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer))
-		dev_err(&dev->dev, "failed to write error node for %s (%s)\n",
-			dev->nodename, printf_buffer);
+	if (path_buffer)
+		xenbus_write(XBT_NIL, path_buffer, "error", printf_buffer);
 
 	kfree(printf_buffer);
 	kfree(path_buffer);