Change targets aosp_atv_arm(64)_ab to aosp_atv_arm(64)

The BoardConfig for generic_arm(64)_ab are going to phased out.
Changes aosp_atv_arm(64)_ab to aosp_atv_arm(64) to avoid using
generic_arm(64)_ab, and keep targets aosp_atv_arm(64)_ab as
aliases.

Bug: 140601829
Test: build pass
Change-Id: Ic8d70b25bda6d3b4957a0030caa32258bbba19e2
Merged-In: Ic8d70b25bda6d3b4957a0030caa32258bbba19e2
5 files changed