Ported drivers list and extract all needed source files. This decouples
ports according to contrib sources and also enables us to revert lxip to
Linux version 3.9, while staying with 3.14 for usb.
Fixes#1285
This patch changes the top-level directory layout as a preparatory
step for improving the tools for managing 3rd-party source codes.
The rationale is described in the issue referenced below.
Issue #1082
