Initial implementation of libaudioamp

* Init the TFA9890 amp.
* Pass on the data from the files in /system/etc/tfa98xx
  to the kernel by an ioctl.
* EQ data present in device-specific header tfa98xx_eq.h
* Also add a standalone executable tfa9890_amp, which
  does all of the above, for when we want to do it
  on demand, directly.

Change-Id: I24d3dfa5b497e2542a2a0877a7795e76cb3d6254