nvme: fix passthrough csi check

The namespace head saves the Command Set Indicator enum, so use that
instead of the Command Set Selected. The two values are not the same.

Fixes: 831ed60c ("nvme: also return I/O command effects from nvme_command_effects")
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>