powerpc: Correct USB support for GE Fanuc SBC610

Support for the SBC610 VPX Single Board Computer from GE Fanuc (PowerPC
MPC8641D).

Fixup to correctly reconfigure USB, provided by an NEC uPD720101, after
device is reset. This requires a set of chip specific registers in the
devices configuration space to be correctly written, enabling all ports
and switching the device to use an external 48-MHz Oscillator.

Signed-off-by: Martyn Welch <martyn.welch@gefanuc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>