drivers: staging: vme: Fixed the using of sizeof

Constructions that looks like
    card = kzalloc(sizeof(struct pio2_card), GFP_KERNEL);
  are changed to
    card = kzalloc(sizeof(*card), GFP_KERNEL);

Signed-off-by: Egor Uleyskiy <egor.ulieiskii@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>