ARM: dts: Freescale: re-license device tree files under GPLv2+/X11

The current GPL only licensing on the device trees makes it very
impractical for other software components licensed under another
license.

To make it easier to reuse them, re-license the the device trees for
Freescale (now NXP) SoCs and boards under GPLv2+/X11 dual license.

Same trend is followed in linux.

Cc: Priyanka Jain <priyanka.jain@nxp.com>
Cc: Mingkai Hu <mingkai.hu@nxp.com>
Cc: York Sun <york.sun@nxp.com>
Signed-off-by: Pankaj Bansal <pankaj.bansal@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>