AT&T today removed the option for unlimited cellular data for all iPad with Wi-Fi + 3G users, but has said eligible users will once again be able to select the plan. On June 7, AT&T changed its data plan pricing structure, removing the $30/month unlimited option which had become familiar to iPhone users and replacing it with a max plan offering 2GB of data for $25 a month. The company quickly clarified that iPhone and iPad users on existing…