boot: zephyr: fix watchdog device typos

Fix typos for IWDG and watchdog0 alias feeding paths.

Signed-off-by: Fabio Utzig <utzig@apache.org>
diff --git a/boot/zephyr/include/mcuboot_config/mcuboot_config.h b/boot/zephyr/include/mcuboot_config/mcuboot_config.h
index ec78aa4..5c132cf 100644
--- a/boot/zephyr/include/mcuboot_config/mcuboot_config.h
+++ b/boot/zephyr/include/mcuboot_config/mcuboot_config.h
@@ -276,7 +276,7 @@
         const struct device* wdt =                                  \
             DEVICE_DT_GET_OR_NULL(DT_INST(0, st_stm32_watchdog));   \
         if (device_is_ready(wdt)) {                                 \
-            wdt_feed(wtd, 0);                                       \
+            wdt_feed(wdt, 0);                                       \
         }                                                           \
     } while (0)
 
@@ -289,7 +289,7 @@
         const struct device* wdt =                            \
             DEVICE_DT_GET(DT_ALIAS(watchdog0));               \
         if (device_is_ready(wdt)) {                           \
-                wdt_feed(wtd, 0);                             \
+            wdt_feed(wdt, 0);                                 \
         }                                                     \
     } while (0)
 #else /* DT_NODE_HAS_STATUS(DT_ALIAS(watchdog0), okay) */