Fix Bfloat16 data conversion for serialization

Signed-off-by: Won Jeon <won.jeon@arm.com>
Change-Id: I52f6fea3e8b4cd5ff0886ccfa12396a680558670
diff --git a/python/serializer/tosa_serializer.py b/python/serializer/tosa_serializer.py
index 7122216..34178c5 100644
--- a/python/serializer/tosa_serializer.py
+++ b/python/serializer/tosa_serializer.py
@@ -947,9 +947,8 @@
             np_arr = np.array(data, dtype=np.float32)
             u8_data.extend(np_arr.view(np.uint8))
         elif dtype == DType.BF16:
-            for val in data:
-                np_arr = np.array(data, dtype=bfloat16)
-                u8_data.extend(np_arr.view(np.uint8))
+            np_arr = np.array(data, dtype=bfloat16)
+            u8_data.extend(np_arr.view(np.uint8))
         elif dtype == DType.FP8E4M3:
             for val in data:
                 val_f8 = np.array(val).astype(float8_e4m3fn).view(np.uint8)