nvme-pci: fix freeze accounting for error handling

A reset on a live device experiencing a link error still needs to have
the queue freeze state started for the subsequent reinitialization. Skip
only the register read if the device is not present instead of bypassing
the freeze checks.

Fixes: b98235d3

 ("nvme-pci: harden drive presence detect in nvme_dev_disable()")
Reported-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Tested-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>