Add patch found in Teltonika RUT9_R_00.07.01.4 GPL SDK download[1]
adding USB IDs of the MeigLink SLM750 to the relevant kernel drivers.
Newer versions of Teltonika's 2G/3G/4G RUT9XX WWAN router series come
with this kind of modem.
[1]: https://wiki.teltonika-networks.com/view/GPL
Signed-off-by: Daniel Golle <daniel@makrotopia.org>