Revert "Add MIPS64r6 support for libpixelflinger"

This reverts commit ab5265ebe65eac3b9555eaa3f425cf8e2759d3b3.

This broke the mips64 build (which, stupidly, I hadn't tested):

  system/core/libpixelflinger/codeflinger/MIPS64Assembler.h:24:35: fatal error: tinyutils/KeyedVector.h: No such file or directory
   #include "tinyutils/KeyedVector.h"

Change-Id: I4fa1c04e196592fd1ef893a83c75261a55d32290
32 files changed