io_uring: fix casts to io_req_flags_t

Apply __force cast to restricted io_req_flags_t type to fix
the following sparse warning:

io_uring/io_uring.c:2026:23: sparse: warning: cast to restricted io_req_flags_t

No functional changes intended.
Signed-off-by: Min-Hua Chen <minhuadotchen@gmail.com>
Link: https://lore.kernel.org/r/20240922104132.157055-1-minhuadotchen@gmail.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -2041,7 +2041,7 @@ static int io_init_req(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	req->opcode = opcode = READ_ONCE(sqe->opcode);
 	/* same numerical values with corresponding REQ_F_*, safe to copy */
 	sqe_flags = READ_ONCE(sqe->flags);
-	req->flags = (io_req_flags_t) sqe_flags;
+	req->flags = (__force io_req_flags_t) sqe_flags;
 	req->cqe.user_data = READ_ONCE(sqe->user_data);
 	req->file = NULL;
 	req->rsrc_node = NULL;