nvme: introduce NVME_QUIRK_IGNORE_DEV_SUBNQN

If a device provides an NQN it is expected to be globally unique.
Unfortunately some firmware revisions for Intel 760p/Pro 7600p devices did
not satisfy this requirement.  In these circumstances if a system has >1
affected device then only one device is enabled.  If this quirk is enabled
then the device supplied subnqn is ignored and we fallback to generating
one as if the field was empty.  In this case we also suppress the version
check so we don't print a warning when the quirk is enabled.

Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: James Dingwall <james@dingwall.me.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>

drivers/nvme/host/nvme.h

@@ -90,6 +90,11 @@ enum nvme_quirks {
 	 * Set MEDIUM priority on SQ creation
 	 */
 	NVME_QUIRK_MEDIUM_PRIO_SQ		= (1 << 7),
+
+	/*
+	 * Ignore device provided subnqn.
+	 */
+	NVME_QUIRK_IGNORE_DEV_SUBNQN		= (1 << 8),
 };
 
 /*