TQM5200: Call usb_cpu_init() during board init

usb_cpu_init() configures GPS USB pins, clocks, etc. and
is required for proper operation of kernel USB subsystem.
This setup was previously done in the kernel by the fixup
code which is being removed, thus low level init must be
done by U-boot now.

Signed-off-by: Marian Balakowicz <m8@semihalf.com>