kernel: add support MeigLink SLM828 modem

kernel: add support MeigLink SLM828 modem

Another Qualcomm-based USB-connected modem, offering endpoints
 0 : rndis_host (link to voip subsystem listening on 169.254.5.100)
 1 : rndis_host (?)
 2 : option (?)
 3 : option (at)
 4 : option (at)
 5 : option (?)
 6 : GobiNet (qmi)
 7 : ?

Add support for this modem in rndis_host, option and qmi_wwan driver
which allows the modem to be used with ModemManager.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit f32baf6a65fbe294b9eb7b93f39b2aea1c3402ae)