scripts: Make object string conversion array const

Prevents unused var warnings by changing to be a constant.

Change-Id: Ie8f6cc837dd589074ae2278de34d4bd0a3e66236
diff --git a/scripts/helper_file_generator.py b/scripts/helper_file_generator.py
index f4f555c..fc32ff2 100644
--- a/scripts/helper_file_generator.py
+++ b/scripts/helper_file_generator.py
@@ -551,7 +551,7 @@
 
         # Output name string helper
         object_types_header += '// Array of object name strings for OBJECT_TYPE enum conversion\n'
-        object_types_header += 'static const char *object_string[kVulkanObjectTypeMax] = {\n'
+        object_types_header += 'static const char * const object_string[kVulkanObjectTypeMax] = {\n'
         object_types_header += '    "Unknown",\n'
         for item in self.object_types:
             fixup_name = item[2:]