This white stuff can be due to smegma or balanitis skin, smegma is produced by penis glands that appears under foreskin. You should use any cosmetics on the penis, instead use some topical antimicrobials like Bacitracin or Lotrimin. Also retract the foreskin daily and soak in warm water to clean penis and foreskin. It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor.