net: qmi_wwan: add BroadMobi BM806U 2020:2033

BroadMobi BM806U is an Qualcomm MDM9225 based 3G/4G modem.
Tested hardware BM806U is mounted on D-Link DWR-921-C3 router.
The USB id is added to qmi_wwan.c to allow QMI communication with
the BM806U.

Tested on 4.14 kernel and OpenWRT.

Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>