Error processing run file with bcl2fastq - Unable to open '.../RunInfo.xml' file for reading
I repro the error.
ls /ml


ls: cannot access '/ml': No such file or directory

If run
bcl2fastq --runfolder-dir ./data/201109_NB551126_0128_AH5G5KBGXF --sample-sheet ./SampleSheet.csv  --no-lane-splitting --barcode-mismatches 0

I suspect it will work.
At present you are attempting to call a directory /data, which doesn't exit. If you type ls /etc that will work. The difference between ./data and /data in a file structure is alot, but on a command line it appears minimal.

Wait ... if that doesn't work .. because I suspect the calling directory is data then the following will,
bcl2fastq --runfolder-dir ./201109_NB551126_0128_AH5G5KBGXF --sample-sheet ./SampleSheet.csv  --no-lane-splitting --barcode-mismatches 0

OR
bcl2fastq --runfolder-dir ./data/201109_NB551126_0128_AH5G5KBGXF --sample-sheet ./data/SampleSheet.csv  --no-lane-splitting --barcode-mismatches 0

It depends on the path where you are making the call. You could sort this out using $PWD or just echo $PWD then copy and paste the path name.