lineage: Move QC board variables earlier

These variables are usually set in a device's BoardConfig, setting them
in qcom_target is at the very end of the "configuration process" which
results in them being unavailable to plenty of other configuration
"things" (ex. soong namespaces or soong config). Move them to right
after a device's BoardConfig has been found and loaded.

Change-Id: Iddd731202d22ed3f8eb010197ce20d3c75a1f40a