In a previous commit, a check was added to ensure modem was properly
attached to packet service before initializing PPP. Failure to perform
this check can lead to the dreaded 'NO CARRIER' issue.
While this is a nice idea, the implementation was lacking because when
the check failed, the entire modem initialization procedure was
restarted from square one. For modems/bearers that were slow to attach,
this is potentially disastrous. The proper solution is to loop only the
'AT+CGATT?' part until it succeeds, or fails N times.
This commit implements this looping behavior (using the work queue).
Signed-off-by: Benjamin Lindqvist <benjamin.lindqvist@endian.se>
28ac1f70bf