fibocom: Check RNDIS state before connecting

The ECM dialling guide requires to check whether RNDIS is already active before attempting to establish an ECM/RNDIS connection. If it is active and the active profile does not match our desired settings (IP family, APN, ...) we error out.

Signed-off-by: Sven Schwermer sven.schwermer@disruptive-technologies.com

I'd like to get some opinions on this approach. There is currently one problem with disconnecting the bearer if +GTRNDIS? reported the PDP context to be already active and returning early (mm-broadband-bearer-fibocom-ecm.c, line 131). The problem is that priv->profile_id is not saved in the MMBroadbandBearer object which is passed to MMFibocomBroadbandBearerEcm::disconnect_3gpp. There is currently no way for the derived class to set the profile ID from MMFibocomBroadbandBearerEcm::connect_3gpp. Should the base class use the profile ID from MMBearerConnectResult to set its private profile ID variable?