What is this called when my neck goes straight and I have no chin line? And what can be done for it? (Photos)

A full set of facial photographs in a chin neutral position are usually required to make a determination about what the can be accomplished with a surgical procedure. A neck lift procedure can accomplish removal of fatty deposits above and below the platysma muscle in addition to a platysma plasty. If there is excess skin present, then a lower face and neck lift is required. For more information  and many  before and after next lift examples, please see the link and the video below

Assuming you do not want any form go chin augmentation, which is just a complement to the procedure that you do need, is the need for a neck lift. Liposuction alone would be inadequate as you have too much loose skin particularly if you are not going to increase the projection of your chin. (a sliding genioplasty is the preferred procedure in your case not a chin implant as you need the submental musculature stretched out to help your neck)