Added the explicit support for auth NONE.
It needs to be added in all drivers/*/gprs-context.c atoms.
This method is already supported by all atoms that support
authentication (ie, all but Sierra' swmodem driver).
The behavior is left unchanged in case of inconsistent parameters:
if username is empty, then fallback to auth NONE.
The U-Blox documentation specifies the following:
* get interface ip and dns from +CGDCONTRDP
* get gw ip and netmask from +UIPADDR
However, different firmware versions have different befaviour:
* On newer firmware, +UIPADDR returns error. But it's possible to configure
gateway ip == ipterface ip (read from CGDCONTRDP).
* On older firmware, we can actually use the commands specified in the
docs.
This patch runs +CGDCONTRDP, configures everything and then tries to run
+UIPADDR. In that works, reconfigures gw ip and netmask.
For now the driver works only with bridged mode for 2G/3G.
Once it activates the context it reads the ip, netmask,
gw, dns and sets them in the context settings.