[mlir][NFC] Remove redundant insertion point changes

These insertion points were added in #146551 and #146908 to support the one-shot dialect conversion driver which performs changes to the IR immediately and would otherwise invalidate previous insertion points.

Since then, the insertion point has been made resilient against op erasure (#146955) making the changes now redundant.

Author: zero9178

mlir/lib/Conversion/SPIRVToLLVM/ConvertLaunchFuncToLLVMCalls.cpp

@@ -267,9 +267,7 @@ class GPULaunchLowering : public ConvertOpToLLVMPattern<gpu::LaunchFuncOp> {
       copyInfo.push_back(info);
     }
     // Create a call to the kernel and copy the data back.
-    Operation *callOp = rewriter.replaceOpWithNewOp<LLVM::CallOp>(
-        op, kernelFunc, ArrayRef<Value>());
-    rewriter.setInsertionPointAfter(callOp);
+    rewriter.replaceOpWithNewOp<LLVM::CallOp>(op, kernelFunc, ArrayRef<Value>());
     for (CopyInfo info : copyInfo)
       copy(loc, info.src, info.dst, info.size, rewriter);
     return success();

mlir/lib/Conversion/TosaToLinalg/TosaToLinalgNamed.cpp

@@ -802,7 +802,6 @@ class MaxPool2dConverter : public OpConversionPattern<tosa::MaxPool2dOp> {
         ValueRange{paddedInput, fakeWindowDims}, filledEmptyTensor, strideAttr,
         dilationAttr);
 
-    rewriter.setInsertionPointAfter(op);
     NanPropagationMode nanMode = op.getNanMode();
     rewriter.replaceOp(op, resultOp);