When suspending, save & restore as many registers as we can from the

When suspending, save & restore as many registers as we can from the
pciide front-ends chips.  More registers will have to added here, chip
by chip (warning messages about unknown chipsets, on resume, mean that
you should talk to me).  Also call the wdc back-end (our child) to have
it reset the controller properly on resume.  This makes all pciide that
we've tested unsuspend.
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