complete_rqe: Remove a race condition in RAID-4 and RAID-5 where a

complete_rqe: Remove a race condition in RAID-4 and RAID-5 where a
	request could be deallocated before the top half had finished
	issuing it.  The problem seems only to happen with IDE drives
	and vn devices, but theoretically it could happen with any
	drive.  This is the most important part of a possible series
	of fixes designed to remove race conditions without locking
	out interrupts for longer than absolutely necessary.

Reported-by:	       sos
Fix-supplied-by:       dillon