USB: option: add ZTE MF821D

commit 09110529780890804b22e997ae6b4fe3f0b3b158 upstream.

Sold by O2 (telefonica germany) under the name "LTE4G"

Tested-by: Thomas Schäfer <tschaefer@t-online.de>
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>