riscv: Enable watchdog for the k210

This enables the necessary config options.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/board/sipeed/maix/Kconfig b/board/sipeed/maix/Kconfig
index 2cdea8e..adf6abb 100644
--- a/board/sipeed/maix/Kconfig
+++ b/board/sipeed/maix/Kconfig
@@ -69,4 +69,6 @@
 	imply EFI_PARTITION
 	imply CMD_PART
 	imply CMD_FS_GENERIC
+	imply WDT
+	imply DESIGNWARE_WATCHDOG
 endif