Initial commit of Z Ultra Google Play Edition

Change-Id: Id3b62451aac5cc657d69e2331a86b0a5cc6c2ad8
Change product model to C6806

* What I made up looked good, but this is what it actually is.

Change-Id: I47c974f1b45b604a5f143f5c2c26ed595a3f99c0
dedupe makefile rules

* What we had in togari_gpe.mk is the same as togari.mk, so
  just include that rather than copy-paste the rules.

Change-Id: I8e5c2e8457f9e4662c2d18efeefaab96c11327aa
Use "include" instead of "-include" wherever appropriate

* When using "-include", make ignores a makefile which does not
  exist, with no error message.
* Use "include" for all makefiles which are essential for a
  working build.

Change-Id: Ic00ba2e9246da3ec47102f79b9c2725ed155b4cf