MIPS: Octeon: Fix compile error when USB is not enabled.

Move all USB platform code to one place within the file.

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/15406/


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