Remove unnecessary use of designated initializer

Change-Id: I16de9223e59e46ad9fb25bd280a175cd50af913d
diff --git a/src/ethosu_device_u55.c b/src/ethosu_device_u55.c
index 0930948..87add7e 100644
--- a/src/ethosu_device_u55.c
+++ b/src/ethosu_device_u55.c
@@ -66,7 +66,7 @@
 
 enum ethosu_error_codes ethosu_dev_get_config(struct ethosu_device *dev, struct ethosu_config *config)
 {
-    struct config_r cfg = {.word = 0};
+    struct config_r cfg = {0};
 
     cfg.word = ethosu_dev_read_reg(dev, NPU_REG_CONFIG);