- Move SMP check to software_suspend() (from software_resume()), so we will
  not even attempt to sleep with it enabled.
- Make software_resume() a late initcall, removing the explicit call from
  prepare_namespace(). 
- Initialize software_suspend_enabled to 1, instead of doing it manually in
  software_resume().
- Don't explicitly initialzie resume_file.
- Remove resume_status variable, as we can simply check for (non-) NULL 
  resume_file string. 
- "noresume" setup function changed to simply zero first byte of resume_file
  string, simplifying logic.
- Don't attempt to reset swap signature if noresume is specified.
  - Downstream function (bdev_write_page() wasn't implemented anyway, so we
    can just remove that also).

If noresume is specified, there will still be a suspend image left on the 
swap partition. It may behoove us to never reset the swap signature, and 
always leave the image intact on the disk, since it is a valid snapshot 
that we can resume from at anytime. 

This unconditional behavior would force the user to add 'mkswap <part>' to
their init scripts to reset the partition to swap use. IMO, this is better
anyway.