x86: mrst: Add Moorestown specific reboot/shutdown support

Moorestowns needs to use a special IPC command to reboot or shutdown the
platform.

Signed-off-by: Alek Du <alek.du@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
LKML-Reference: <20101110164928.6365.94243.stgit@localhost.localdomain>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>