ARM: zynq: DT: Fix binding for cadence WDT

Based on:
"devicetree: Add Cadence WDT devicetree bindings documentation"
(sha1: 191891c0)

- compatible string is cdns,wdt-r1p2
- remove device_type property
- remove int reset property (reset-on-timeout is bool)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Series-to: arm-soc
Signed-off-by: Michal Simek <michal.simek@xilinx.com>