MIPS: Define some more PIIX4 registers & values

This patch simply adds definitions for some I/O registers in the PIIX4
PM device, and the magic data for a special cycle which must occur on
the PCI bus in order for the PIIX4 to enter a suspend state.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6903/


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