ARM: socfpga: dts: add watchdog0+1

The SoCFPGA has two watchdog timers. Add them to the dtsi.

Signed-off-by: Steffen Trumtrar <s.trumtrar@pengutronix.de>
[dinh: modified patch to have correct irq flag]
Signed-off-by: Dinh Nguyen <dinguyen@altera.com>