[PATCH][next] nvme-loop: Avoid -Wflex-array-member-not-at-end warning

["Gustavo A. R. Silva" <gustavoars@kernel.org>]

-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.

Move the conflicting declaration to the end of the structure. Notice
that `struct nvme_loop_iod` is a flexible structure --a structure
that contains a flexible-array member.

Fix the following warning:

drivers/nvme/target/loop.c:36:33: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 drivers/nvme/target/loop.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index a5c41144667c..d02b80803278 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c
@@ -33,10 +33,12 @@ struct nvme_loop_ctrl {
 
 	struct list_head	list;
 	struct blk_mq_tag_set	tag_set;
-	struct nvme_loop_iod	async_event_iod;
 	struct nvme_ctrl	ctrl;
 
 	struct nvmet_port	*port;
+
+	/* Must be last --ends in a flexible-array member. */
+	struct nvme_loop_iod	async_event_iod;
 };
 
 static inline struct nvme_loop_ctrl *to_loop_ctrl(struct nvme_ctrl *ctrl)
-- 
2.43.0