fsl/usb: Move USB internal phy definitions to fsl_usb.h

fsl_usb.h file created to share data bewteen usb platform code
and usb ip driver. Internal phy structure definitions moved to
this file

Signed-off-by: Ramneek Mehresh <ramneek.mehresh@freescale.com>
Acked-by: York Sun <yorksun@freescale.com>