Update Image Compression Control sample tutorial (#1096)

When querying for image compression support, `VK_IMAGE_COMPRESSION_FIXED_RATE_DEFAULT_EXT` should be used, as shown in the [extension proposal](https://docs.vulkan.org/features/latest/features/proposals/VK_EXT_image_compression_control.html#_examples)

samples/performance/image_compression_control/README.adoc

@@ -131,7 +131,7 @@ To query if a particular image supports fixed-rate compression, add a https://re
 VkImageCompressionPropertiesEXT supported_compression_properties{VK_STRUCTURE_TYPE_IMAGE_COMPRESSION_PROPERTIES_EXT};
 
 VkImageCompressionControlEXT compression_control{VK_STRUCTURE_TYPE_IMAGE_COMPRESSION_CONTROL_EXT};
-compression_control.flags = VK_IMAGE_COMPRESSION_FIXED_RATE_EXPLICIT_EXT;
+compression_control.flags = VK_IMAGE_COMPRESSION_FIXED_RATE_DEFAULT_EXT;
 
 VkPhysicalDeviceImageFormatInfo2 image_format_info{VK_STRUCTURE_TYPE_PHYSICAL_DEVICE_IMAGE_FORMAT_INFO_2};
 image_format_info.format = VK_FORMAT_R8G8B8_UNORM;