Rename mainline_system(.*).mk to generic_system(.*).mk am: 1a595e0157

Original change: https://android-review.googlesource.com/c/device/google_car/+/1413371

Change-Id: I0d44970326f4c8391459d98140f817235816759c
tree: 81ad9403a38531d2bbb132482cbbbe279f6d1fe4
  1. AndroidProducts.mk
  2. OWNERS
  3. coral_car/
  4. crosshatch_car/