[clang] [CIR][NFC] Simplify BoolAttr builders (PR #136366)

[Henrich Lauko via cfe-commits]

================
@@ -692,9 +692,7 @@ mlir::LogicalResult CIRToLLVMConstantOpLowering::matchAndRewrite(
     // during a pass as long as they don't live past the end of the pass.
     attr = op.getValue();
   } else if (mlir::isa<cir::BoolType>(op.getType())) {
-    int value = (op.getValue() ==
-                 cir::BoolAttr::get(getContext(),
-                                    cir::BoolType::get(getContext()), true));
+    int value = (op.getValue() == cir::BoolAttr::get(getContext(), true));
----------------
xlauko wrote:

yeah, probably even nicer is

```
else if (auto ba = mlir::dyn_cast<cir::BoolAttr>(op.getValue())) {
    attr = rewriter.getIntegerAttr(typeConverter->convertType(op.getType()), ba.getValue());
```

https://github.com/llvm/llvm-project/pull/136366