Added TPA3126D2

Created by: LJJS

Added the TPA3126D2 from Texas Instruments.

---

Thanks for creating a pull request to contribute to the KiCad libraries! To speed up integration of your PR, please check the following items:

• Provide a URL to a datasheet for the symbol(s) you are contributing http://www.ti.com/lit/ds/symlink/tpa3126d2.pdf
• An example screenshot image is very helpful
• Ensure that the associated footprints match the official footprint library
• If there are matching footprint PRs, provide link(s) as appropriate https://github.com/KiCad/kicad-footprints/pull/947
• Check the output of the Travis automated check scripts - fix any errors as required