This is a response from Freescale Tech Support:
---------------------------------------------------------------
Hi Michael:
USB_DM and USB_DP are the only pins needed for a direct connection to a USB connector (type A and B). In case you're interested in an external usb phy (not using phy-on-chip), which I don't think so, those other lines are used for. Seeing m52210demo board schematic would help to understand this.
If you have further questions, please let me know.
Regards,
PAOLO RENZO
Technical Support
Freescale Semiconductor