code_relocation: Fix Warning

The script is generatinga void instead of return. Fix it.

Signed-off-by: Carlo Caione <ccaione@baylibre.com>
diff --git a/scripts/build/gen_relocate_app.py b/scripts/build/gen_relocate_app.py
index c22dda8..8177b5c 100644
--- a/scripts/build/gen_relocate_app.py
+++ b/scripts/build/gen_relocate_app.py
@@ -392,7 +392,7 @@
     if code_generation["copy_code"]:
         code_string += DATA_COPY_FUNCTION.format(code_generation["copy_code"])
     else:
-        code_string += DATA_COPY_FUNCTION.format("void;")
+        code_string += DATA_COPY_FUNCTION.format("return;")
     if code_generation["zero_code"]:
         code_string += BSS_ZEROING_FUNCTION.format(code_generation["zero_code"])
     else: