Minor tweaks to the resume code. Previous commit reverted alignment back

Minor tweaks to the resume code.  Previous commit reverted alignment back
to 4.  There is no need to be more strict at assembly time since we copy
the code anyway to a private page.

* Clear the direction flag and eflags.  Probably not necessary but it won't
  hurt to be safe.
* Add prefixes to all instructions to prevent any assembler mistakes.
* Remove zeroing of eax - edi.  We use those registers immediately after
  to transfer values to protected mode so this was pointless.
* Update comments to reflect info found during code review.