qmi_wwan: add support for Quectel EG91

This adds the USB id of LTE modem Quectel EG91. It requires the
same quirk as other Quectel modems to make it work.

Signed-off-by: Matevz Vucnik <vucnikm@gmail.com>
Acked-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>