ARM: dts: tpc: Device tree description of the iMX6Q TPC board

This commit adds device tree description of Kieback & Peter GmbH
iMX6Q TPC board.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>