Instead of getting it from the MMIfaceModemMessaging when the
SMS is stored. This flattens dependencies between MMBaseSms and
MMIfaceModemMessaging.
Signed-off-by: Dan Williams <dan@ioncontrol.co>
Simplify MMBaseSms (making it easier to use from testcases) by
splitting the AT-specific code into MMSmsAt rather than keeping
it in the base class.
Signed-off-by: Dan Williams <dan@ioncontrol.co>