Sometime later when this repository was noticed on Github, someone noticed the source was a derivation of one of the existing Linux FAT filesystem drivers. In other words, under the terms of the GPL it is derived code. The fact it was only previously distributed in binary form does not excuse this: Samsung were distributing GPL derived code in violation of the license.
So this clears things up a little bit. What I don't understand now is the usefulness of this code. For example, could it potentially be merged upstream? If not, then why not? If it can be distributed under the GPL independently, I don't understand why it couldn't get shipped with Linux.
The fact this driver exists "legitimately open source" now, yet is still covered by patents, confuses me a bit.