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/configs/taurus_defconfig b/configs/taurus_defconfig
index ee5da43..e53e075 100644
--- a/configs/taurus_defconfig
+++ b/configs/taurus_defconfig
@@ -61,3 +61,6 @@
 CONFIG_USB_GADGET_PRODUCT_NUM=0x02d2
 CONFIG_USB_GADGET_DOWNLOAD=y
 CONFIG_USE_TINY_PRINTF=y
+CONFIG_WDT=y
+CONFIG_WDT_AT91=y
+CONFIG_AT91_HW_WDT_TIMEOUT=y