Low leves of probability observed after modelling.Is it right to scale the probability
It sometimes happens that a classification model will output probability estimates that are all in the low range. That means the model does not make any predictions that it is very sure are the positive class. Since only 10% of your data falls into the positive class, it appears to be a difficult problem to predict using your model. 

Do not transform the probability estimates. When this happened to me multiple times, the predictions were still useful. For example, you may be interested in the highest 10% of predictions. You can always set your prediction threshold anywhere between 0 and 1.