board: add support for WarPboard

This is a set of patch to add support for warpboard
(Freescale board based on imx6sl)

The patch contains :
  - defconfig for warpboard
  - linux patches from Fabio Estevam to fix device tree due to last change on
  warpboard schematics (rev 1.12) and to fix kernel imx_v6_v7 defconfig which
  use incorrect hci protocol
  - specific firmware file for warpboard bluetooth
  nvram : brcmfmac4330-sdio.txt

Origin of nvram config file for wifi :
https://github.com/Freescale/meta-fsl-arm-extra



[Thomas: misc rewording/improvements in the README file.]

Signed-off-by: Arthur LAMBERT <arthur@dreem.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>