MIPS: OCTEON: Fix breakage due to 8250 changes.

The changes in linux-next removing serial8250_register_port() cause
OCTEON to fail to compile.

Lets make OCTEON use the new serial8250_register_8250_port() instead.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: Alan Cox <alan@linux.intel.com>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>