nvme-apple: only reset the controller when RTKit is running

NVMe controller register access hangs indefinitely when the co-processor
is not running. A missed reset is preferable over a hanging thread since
it could be recoverable.

Signed-off-by: Janne Grunau <j@jannau.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>