ARM: dts: Re-license SolidRun iMX6 platform DT GPL v2/X11

Update SolidRun iMX6 platforms DT descriptions to be dual-licensed.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Rabeeh Khoury <rabeeh@solid-run.com>
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>