USB: serial: pl2303: add device id for ztek device

commit 91fcb1ce420e0a5f8d92d556d7008a78bc6ce1eb upstream.

This adds a new device id to the pl2303 driver for the ZTEK device.

Reported-by: Mike Chu <Mike-Chu@prolific.com.tw>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>