keymaster: Add keymaster implementation

Initial implementation of keymaster HAL APIs published in keymaster.h

Bug: 7106634
Change-Id: I1b1f611f1988212ce5f6f7f03b9a59ca652d92cf
Signed-off-by: Iliyan Malchev <malchev@google.com>
Merge tag 'android-4.2.2_r1' into jb422

Android 4.2.2 release 1