Linphone: remove nonfreepdep warning, it's not the case anymore

I explicitly removed the nonfree dep feature of the fdroid build to avoid such warnings, eg:

rm libs/gcm.jar src/org/linphone/gcm/GCMService.java src/org/linphone/gcm/GCMReceiver.java && \

So I believe the warning should not be present; Fdroid users will have no push notification but that's expected, isn't it?