arm: at91: wdt: Convert watchdog driver to dm/dt

Convert the Watchdog driver for AT91SAM9x processors to support
the driver model and device tree. Changes "CONFIG_AT91SAM9_WATCHDOG"
to new "CONFIG_WDT_AT91" Kconfig option.

Signed-off-by: Prasanthi Chellakumar <prasanthi.chellakumar@microchip.com>
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 02f4e1e..a911dba 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -118,4 +118,14 @@
 	   Select this to enable the IMX and LSCH2 of Layerscape watchdog
 	   driver.
 
+config WDT_AT91
+	bool "AT91 watchdog timer support"
+	depends on WDT
+	help
+	   Select this to enable Microchip watchdog timer, which can be found on
+	   some AT91 devices.
+
+config AT91_HW_WDT_TIMEOUT
+	bool "AT91 watchdog timeout specified"
+	depends on WDT_AT91
 endmenu