ARM: dts: imx: fix PCI bus dtc warnings

dtc recently added PCI bus checks. Fix these warnings.

Signed-off-by: Rob Herring <robh@kernel.org>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>