drivers: watchdog: esp32: Add Watchdog Device tree support

- Add WDT(0,1) to esp32.dtsi
- Extend the module to be able to use WDT(0,1)
- Some minor refactoring due to usage of device tree

Tests:
- samples/drivers/watchdog
- tests/drivers/watchdog/wdt_basic_api

Note:
- timer module interrupt registers shall be removed when
timer driver implemented.

Signed-off-by: Mohamed ElShahawi <ExtremeGTX@hotmail.com>