ARM: dts: gr-peach: Enable ostm0 and ostm1 timers

Enable ostm0 and ostm1 timers to be used as clock source and clockevent
source. The timers provides greater accuracy than the already enabled
mtu2 one.

With these enabled:

clocksource: ostm: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 57352151442 ns
sched_clock: 32 bits at 33MHz, resolution 30ns, wraps every 64440619504ns
ostm: used for clocksource
ostm: used for clock events

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Suggested-by: Chris Brandt <chris.brandt@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>