Bump open source LLVM revision to 398b497cd0e20ca7245bf30c12c761b444581da5

Adjust code for MLIR refactorings.

PiperOrigin-RevId: 301341008
diff --git a/iree/compiler/Dialect/VM/Conversion/ImportUtils.h b/iree/compiler/Dialect/VM/Conversion/ImportUtils.h
index 1e4f8f8..78dbd57 100644
--- a/iree/compiler/Dialect/VM/Conversion/ImportUtils.h
+++ b/iree/compiler/Dialect/VM/Conversion/ImportUtils.h
@@ -158,10 +158,8 @@
   PatternMatchResult matchAndRewrite(
       T op, llvm::ArrayRef<Value> operands,
       ConversionPatternRewriter &rewriter) const override {
-    return succeeded(rewriteToCall(op, Adaptor{operands}, importOp,
-                                   typeConverter, rewriter))
-               ? OpConversionPattern<T>::matchSuccess()
-               : llvm::None;
+    return rewriteToCall(op, Adaptor{operands}, importOp, typeConverter,
+                         rewriter);
   }
 
  protected: