ARM: dts: imx6q-cm-fx6: Relicense under GPLv2/X11

GPLv2-only devicetrees make reuse difficult for software components
licensed under a different license. In particular, the Utilite Pro
devicetree file (which includes imx6q-cm-fx6.dts) is already dual
licensed under GPLv2/X11.

Hence, relicense imx6q-cm-fx6.dts under GPLv2/X11 dual license.

Signed-off-by: Christopher Spinrath <christopher.spinrath@rwth-aachen.de>
Acked-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>