qmi_wwan: Add support for Quectel RM500Q

RM500Q is a 5G module from Quectel, supporting both standalone and
non-standalone modes. The normal Quectel quirks apply (DTR and dynamic
interface numbers).

Signed-off-by: Kristian Evensen <kristian.evensen@gmail.com>
Acked-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>