Rework of SMTC support to make it work with the new clock event system,
allowing "tickless" operation, and to make it compatible with the use of
the "wait_irqoff" idle loop.  The new clocking scheme means that the
previously optional IPI instant replay mechanism is now required, and has
been made more robust.
Signed-off-by: NKevin D. Kissell <kevink@paralogos.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>