If the driver takes care of state saving, don't touch any registers on it.

Optimus (dual-gpu) laptops seem to have their own form of D3cold, but
unfortunately enter it on normal D3 transitions via the ACPI callback.

So when we use runtime PM to transition to D3, the card disappears off
the PCI bus, however we then try to access registers on it in the
runtime suspend finish, which really doesn't work.

This patch checks whether the pci state is saved and doesn't attempt to hit
any registers after that point if it is.

(Looks okay to Rafael)
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>