Further locking improvements for vr(4):

• Add *_locked() entry points as needed to avoid unnecessary lock thrashing.
• Use these entry points wisely.
• Only acquire the lock once when servicing an interrupt.
• Check 'suspended' on interrupt to avoid racing detach.
• Correct a mis-spelled comment.
• Don't take the lock in vr_reset() to avoid lock thrashing in attach.
  • Comment this.

Reviewed by: -net (silence)