[mlir] Use .empty() instead of checking size() == 0.

Based on a finding by ClangTidy readability-container-size-empty check.

mlir/tools/mlir-vulkan-runner/VulkanRuntime.cpp

@@ -104,7 +104,7 @@ LogicalResult VulkanRuntime::countDeviceMemorySize() {
 }
 
 LogicalResult VulkanRuntime::initRuntime() {
-  if (!resourceData.size()) {
+  if (resourceData.empty()) {
     std::cerr << "Vulkan runtime needs at least one resource";
     return failure();
   }