Merge branch 'wwan-improvements'

Sergey Ryazanov says:

====================
net: WWAN subsystem improvements

While working on WWAN netdev creation support, I notice a few things
that could be done to make the wwan subsystem more developer and user
friendly. This series implements them.

The series begins with a WWAN HW simulator designed simplify testing
and make the WWAN subsystem available for a wider audience. The next two
patches are intended to make the code a bit more clearer. This is
followed by a few patches to make the port device naming more
user-friendly. The series is finishes with a set of changes that allow
the WWAN AT port to be used with terminal emulation software.

All changes were tested with the HW simulator that was introduced in
this series, as well as with a Huawei E3372 LTE modem (a CDC-NCM
device), which I finally found on my desk.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>