Huawei: support new voice call related URCs: ^CCALLSTATE and ^CSCHANNELINFO
As seen in the following log: https://lists.freedesktop.org/archives/modemmanager-devel/2020-May/007867.html
E.g. we're currently ignoring ^CSCHANNELINFO
but we can probably use it. And we're not yet handling ^CCALLSTATE
, which can probably help us avoid CLCC
polling.