comgt-ncm: add support for UNISOC SL8563 based TOZED TL70-C

comgt-ncm: add support for UNISOC SL8563 based TOZED TL70-C

TOZED TL70-C is an LTE CAT6 cellular modem based on UNISOC SL8563. UNISOC
was formerly called Spreadtrum hence the manufacturer name detected on the
modem is spreadtrum.

The connect and disconnect commands bring up and down the usb0 interface.
They are Base64 encoded as that's what the AT command accepts. The modem
can do up to 4 APNs by bringing the USB interfaces, usb0 to usb3, up.

Setting the USB interfaces up:

connmanctl ndisdial AT^NDISDUN="usb0",1,1
connmanctl ndisdial AT^NDISDUN="usb1",1,2
connmanctl ndisdial AT^NDISDUN="usb2",1,3
connmanctl ndisdial AT^NDISDUN="usb3",1,4

Setting the USB interfaces down:

connmanctl ndisdial AT^NDISDUN="usb0",0,1
connmanctl ndisdial AT^NDISDUN="usb1",0,2
connmanctl ndisdial AT^NDISDUN="usb2",0,3
connmanctl ndisdial AT^NDISDUN="usb3",0,4

Co-developed-by: Andre Cruz <me@1conan.com>
Signed-off-by: Andre Cruz <me@1conan.com>
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>