NVMe: Device specific stripe size handling

We have an nvme device that has a concept of a stripe size. IO requests
that do not transfer data crossing a stripe boundary has greater
performance compared to IO that does cross it. This patch sets the
stripe size for the device if the device and vendor ids match one with
this feature and splits IO requests that cross the stripe boundary.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>

include/linux/nvme.h

@@ -536,6 +536,7 @@ struct nvme_dev {
 	char model[40];
 	char firmware_rev[8];
 	u32 max_hw_sectors;
+	u32 stripe_size;
 	u16 oncs;
 };