of: overlay: kmemleak in dup_and_fixup_symbol_prop()

kmemleak reports several memory leaks from devicetree unittest.
This is the fix for problem 4 of 5.

target_path was not freed in the non-error path.

Fixes: e0a58f3e ("of: overlay: remove a dependency on device node full_name")
Reported-by: NErhard F. <erhard_f@mailbox.org>
Signed-off-by: NFrank Rowand <frank.rowand@sony.com>
Signed-off-by: NRob Herring <robh@kernel.org>

drivers/of/overlay.c

@@ -261,6 +261,8 @@ static struct property *dup_and_fixup_symbol_prop(
 
 	of_property_set_flag(new_prop, OF_DYNAMIC);
 
+	kfree(target_path);
+
 	return new_prop;
 
 err_free_new_prop: