ARM: dts: N9/N950: fix boot hang with 3.14-rc1

N9/N950 does not boot anymore with 3.14-rc1, because SoC compatible
property is missing. Fix that.

Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Reviewed-by: Nishanth Menon <nm@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>