Reserve enums for cl_ext_image_tiling_control (#764)

Change-Id: I95e066dede45281f453a6ce2f30deeb309bb9bc3

Author: kpet

xml/cl.xml

@@ -2114,7 +2114,8 @@ server's OpenCL/api-docs repository.
         <enum value="0x4231"        name="CL_DEVICE_SINGLE_FP_ATOMIC_CAPABILITIES_EXT"/>
         <enum value="0x4232"        name="CL_DEVICE_DOUBLE_FP_ATOMIC_CAPABILITIES_EXT"/>
         <enum value="0x4233"        name="CL_DEVICE_HALF_FP_ATOMIC_CAPABILITIES_EXT"/>
-            <unused start="0x4234" end="0x423F"/>
+            <unused start="0x4234" end="0x4236" comment="Reserved for cl_ext_image_tiling_control"/>
+            <unused start="0x4237" end="0x423F"/>
     </enums>
 
     <enums start="0x4240" end="0x424F" name="enums.4240" comment="Reserved for ICD Loader Layers">