NVMe: Fix uninitialized iod compiler warning

Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
diff --git a/drivers/block/nvme.c b/drivers/block/nvme.c
index af1ef39..6c0eb76 100644
--- a/drivers/block/nvme.c
+++ b/drivers/block/nvme.c
@@ -1159,7 +1159,7 @@
 	struct nvme_admin_cmd cmd;
 	struct nvme_command c;
 	int status, length;
-	struct nvme_iod *iod;
+	struct nvme_iod *uninitialized_var(iod);
 
 	if (!capable(CAP_SYS_ADMIN))
 		return -EACCES;