Add gsi_arm.mk product makefile

GSI product makefile for compliance GSI release.

Bug: 177495407
Test: lunch gsi_arm-userdebug && m
Test: lunch gsi_arm64-userdebug && m
Test: Boot with gsi_arm64 as system partition on bramble
Change-Id: Ida75e3715427f91153a4f0062cb70d3694dd9a81
2 files changed