MIPS: Octeon: Improve USB reset code for OCTEON II.

At boot time, do a better job of resetting the USB host controller
to make the frequency "eye" diagram more compliant with the USB
standard while making the controller more reliable.

Signed-off-by: Steven J. Hill <steven.hill@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/13831/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>