Improve documentation of nyx_device_info_type_t

- Document which nyx_device_info_type_t queries are constant
- Add documentation for some other enumerants
- "doxygenize" the existing enumerant documentaion

[GF-2811] Remove non-constant fields from device_info.json

Open-webOS-DCO-1.0-Signed-off-by: Herb Kuta <herb.kuta@lge.com>
Open-webOS-DCO-1.0-Signed-off-by: Keith Derrick <keith.derrick@lge.com>
Change-Id: I8e33b65e3847a0e921f3f3d9d8765c5caffb8a96