Fix build of Freescale VPU library

- always use /usr as install prefix
Fix kernel headers include path in alarm/imx-lib
Changed provides array in alarm/gpu-viv-bin-mxq6 to a per-package base
Add Xorg driver for Vivante GPU
Add core/linux-wandboard-fsl

This is a Wandboard kernel taken from https://github.com/wolfgar/linux/
with Vivante GPU 4.6.9p13 driver integration to allow for use of latest
Vivante GPU drivers.
The PKGBUILD comes from CruX <CruX@project-insanity.org.org> while the
config was adapted to work with latest systemd