Raw10/12 CTS tests (#1830)

Add support for cl_ext_image_raw10_raw12 testing
on test_image_streams.

Signed-off-by: John Kesapides <john.kesapides@arm.com>

test_common/harness/imageHelpers.cpp

@@ -288,6 +288,9 @@ uint32_t get_pixel_size(const cl_image_format *format)
             return get_format_channel_count(format) * sizeof(cl_float);
         case CL_UNORM_INT_101010_2: return 4;
 
+        case CL_UNSIGNED_INT_RAW10_EXT:
+        case CL_UNSIGNED_INT_RAW12_EXT: return 2;
+
         default: return 0;
     }
 }