Frequent bathing will only serve to dry the skin more and wash out the natural oils in the coat of the cat.
Johnson's baby shampoo is non irritating for babies but that does not guarantee it is the same for cats sadly.
Generally a top quality diet with as little preservative and corn in it as possible combined with daily brushing and combing should be sufficient for the cat to keep the skin and coat in good condition.
An additional supplement containg the Omega factor specifically for cats can help in the short term dosage
If the danfduff appears to worsen you would be best to have the vet take a look at it as there may be a medical reason for this and there is also a mite known as cheylettia that has the nickname walking dandruff.