[mlir][Bazel] Add missing dependency after 48babe1

Author: akuegel

utils/bazel/llvm-project-overlay/mlir/BUILD.bazel

@@ -6074,6 +6074,7 @@ cc_library(
         ":LLVMDialect",
         ":NVVMOpsIncGen",
         ":NVVMRequiresSMTraitsIncGen",
+        ":PtrDialect",
         ":SideEffectInterfaces",
         ":Support",
         ":ToLLVMIRTranslation",