Workaround for ConversionPatternRewriter::eraseOp issue (#4310)

Using `ConversionPatternRewriter::replaceAllUsesWith` +
`ConversionPatternRewriter::eraseOp` is not supported at the moment, and
will fail an assert after integrating
llvm/llvm-project@2929a29.

The workaround is to use `replaceOp` instead, see:
llvm/llvm-project#155244 (comment)

Author: rkayaith

lib/Dialect/Torch/Transforms/ReduceOpVariants.cpp

@@ -253,8 +253,7 @@ void TorchMatchSpecializedBackendOp::populateSpecializedConversions(
           auto newOp = rewriter.create<Torch::AtenScaledDotProductAttentionOp>(
               op.getLoc(), op->getResultTypes()[0], newOperands,
               op->getAttrs());
-          rewriter.replaceAllUsesWith(op.getResult(0), newOp.getResult());
-          rewriter.eraseOp(op);
+          rewriter.replaceOp(op, {newOp.getResult(), nullptr});
           return success();
         }
         return failure();