ARM: dts: imx6: pbab01: Set USB OTG port to peripheral

Due to a hardware bug preventing the correct detection if the ID pin
the USB OTG port cannot be used in otg mode. It can either be set to
host or peripheral. Set it to peripheral so vbus is disabled by default.

Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>