Nets owner Mikhail Prokhorov has his struggling Brooklyn squad on his mind even while he’s on a lavish winter getaway. Sources say the Russian billionaire has been spotted skiing in Courchevel, France — and that when a fellow vacationer asked the mogul in Russian about his NBA team, he responded by confidently saying, “I’m going to fix it. We will win.” According to reports, Prok interrupted his skiing to come to New York last week to ax coach Avery Johnson. The change at the top seems to have paid off so far: The Nets rebounded with a winning record since interim leader P.J. Carlesimo took over. The action also apparently allowed the owner to head to the slopes again.