usb: webusb: Strip CDC ACM function from the code

CDC ACM is not needed in webusb, communication is going through Bulk
endpoints. Endpoint numbers stay the same only Interface number
changed, so basically only this change is needed:

-        .then(() => this.device_.claimInterface(2))
+        .then(() => this.device_.claimInterface(0))

this.device_.claimInterface({2,0}) apart from removing serial port
commands.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>