pathmap: Point the path maps directly to the correct sources

Qcom provides multiple board variants.
Add a generic way of mapping these variants to minimise the amount
of branches that are required for each qcom hardware repo.

This will also make it so frameworks don't have to do checks on
variants or whether BOARD_USES_QCOM_HARDWARE is set, leading to
cleaner makefiles + less places to update at later stages.

Change-Id: Ic4ed61bbdea9d0b5683502bf84a8410e76858527