[PATCH] smc91x addr config check

  The PAGE_SIZE mask is indeed confusing.  Use the exact mask for
  this context which has nothing to do with memory pages at all.
  Also cast to int since the value to compare with is an int.

  Signed-off-by: Nicolas Pitre <nico@cam.org>
  Signed-off-by: Jeff Garzik <jgarzik@pobox.com>