modem: usb: adding more ACM channels support for IMC XMM6260 modems

The are four usable ports on IMC XMM6260 modems.
The first port is for AT channel (intf 00 and 01).
The second (intf 02 and 03) and the third (intf 04 and 05) is for data interface.
The fourth (intf 06 and 07) be used for modem logging.

Change-Id: I69ccbd0a13c8bfd971f36d7e02d8120da6b1b9a6