commit 35cc83ea upstream.

Enable Silicon Labs Ember VID chips to enumerate with the cp210x usb serial
driver. EM358x devices operating with the Ember Z-Net 5.1.2 stack may now
connect to host PCs over a USB serial link.
Signed-off-by: Nathaniel Ting <nathaniel.ting@silabs.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>