OMAP: dmtimer: enable all timers to be wakeup events

All GP timers on OMAP2/3 can generate wakeup events.  The wakeup status is
cleared in the PRCM interrupt handler.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Paul Walmsley <paul@pwsan.com>