ARM: OMAP: timer: allow gp timer clock-event to be used on both cpus

For coupled cpuidle to work when both cpus are active, it needs a global timer
that can handle events for both cpus.  This timer is used as the broadcast
clock-event when the per-cpu timer hardware stop in low power states.
Set the cpumask of clockevent_gpt to all cpus, set the rating correctly, and
set the irq to allow the clockevent core to determine the affinity of the
timer.

Signed-off-by: Colin Cross <ccross@android.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>