Before we send a hardware reset to the controller, mark all the admin
and I/O queues as being 'in the interrupt handler' so that we know all
interrupt handlers have excited. Once the hardware reset is complete,
unblock the interrupt hanlders so that we can bring the card back
up. This replaces a 100ms sleep that we use for this purpose today,
potentially making reset a little faster as well as safer.

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Note: This assumes that this atomic is the right way to go.
Drew suggested maybe a full mutex, in which case this would change to that idiom.