ARM: dts: imx: Fix boolean properties with values

Boolean properties in DT are present or not present and don't take a value.
A property such as 'foo = <0>;' evaluated to true. IOW, the value doesn't
matter.

It may have been intended that 0 values are false, but there is no change
in behavior with this patch.

Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>