ARM: dts: imx: Use generic node names for Zii dts

The devicetree specification recommends using generic node names.

Some Zii dts files already follow such recommendation, but some don't,
so use generic node names for consistency among the Zii dts files.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>