[mlir] Allow nested regions in inlineRegionAndEmitStore

This is useful for scalar code that uses for/while loops.
This has also been confirmed to work for representing std.pow as an
scf.for loop on gpus.

Differential Revision: https://reviews.llvm.org/D93308

mlir/lib/Dialect/Linalg/Transforms/Loops.cpp

@@ -71,7 +71,6 @@ static void inlineRegionAndEmitStore(OpType op, ArrayRef<Value> indexedValues,
   BlockAndValueMapping map;
   map.map(block.getArguments(), indexedValues);
   for (auto &op : block.without_terminator()) {
-    assert(op.getNumRegions() == 0 && "expected a non-nested region");
     auto *newOp = b.clone(op, map);
     map.map(op.getResults(), newOp->getResults());
   }