If you look at arch/arm/boot/dts/imx53-qsb.dts you will see that USB support is not in place yet.
You can look at arch/arm/boot/dts/imx6q-sabrelite.dts as this board has USB host support.
Then you can try to send your patch to linux-arm-kernel mailing list and we can discuss from there.
Regards,
Fabio Estevam