const-ify make segment ops structures
There is no reason to keep the segment ops structures writable.

*** 186,196 ****
  /*
   * XXX  this struct is used by rootnex_map_fault to identify
   *      the segment it has been passed. So if you make it
   *      "static" you'll need to fix rootnex_map_fault.
   */
! struct seg_ops segdev_ops = {
          .dup            = segdev_dup,
          .unmap          = segdev_unmap,
          .free           = segdev_free,
          .fault          = segdev_fault,
          .faulta         = segdev_faulta,
--- 186,196 ----
  /*
   * XXX  this struct is used by rootnex_map_fault to identify
   *      the segment it has been passed. So if you make it
   *      "static" you'll need to fix rootnex_map_fault.
   */
! const struct seg_ops segdev_ops = {
          .dup            = segdev_dup,
          .unmap          = segdev_unmap,
          .free           = segdev_free,
          .fault          = segdev_fault,
          .faulta         = segdev_faulta,