MIPS: OCTEON: Platform support for OCTEON III USB controller

MIPS: OCTEON: Platform support for OCTEON III USB controller

Add all the necessary platform code to initialize the dwc3
USB host controller. This code initializes the clocks and
performs a reset on the USB core and PHYs. The driver code
in 'drivers/usb/dwc3' is where the real driver lives.

Signed-off-by: Steven J. Hill <steven.hill@cavium.com>
Acked-by: David Daney <david.daney@cavium.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15108/
Signed-off-by: James Hogan <james.hogan@imgtec.com>