ARM: dts: OMAP5: Specify nonsecure PPI IRQ for arch timer

Specify both secure as well as nonsecure PPI IRQ for arch
timer. This fixes the following errors seen on DT OMAP5 boot..

[    0.000000] arch_timer: No interrupt available, giving up

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Signed-off-by: Benoit Cousson <benoit.cousson@linaro.org>