nvme: fix the definition of the doorbell buffer config support bit

NVMe 1.3 specification defines the Optional Admin Command Support feature
flags, bit 8 set to '1' then the controller supports the Doorbell Buffer
Config command. Bit 7 is used for Virtualization Mangement command.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Fixes: f9f38e3 ("nvme: improve performance for virtual NVMe devices")
Cc: stable@vger.kernel.org

include/linux/nvme.h

@@ -254,7 +254,7 @@ enum {
 	NVME_CTRL_VWC_PRESENT			= 1 << 0,
 	NVME_CTRL_OACS_SEC_SUPP                 = 1 << 0,
 	NVME_CTRL_OACS_DIRECTIVES		= 1 << 5,
-	NVME_CTRL_OACS_DBBUF_SUPP		= 1 << 7,
+	NVME_CTRL_OACS_DBBUF_SUPP		= 1 << 8,
 };
 
 struct nvme_lbaf {