io_uring/notif: shrink account_pages to u32

->account_pages is the number of pages we account against the user
derived from unsigned len, it definitely fits into unsigned, which saves
some space in struct io_notif_data.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/19f2687fcb36daa74d86f4a27bfb3d35cffec318.1713185320.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: isilence

io_uring/notif.h

@@ -13,7 +13,8 @@
 struct io_notif_data {
 	struct file		*file;
 	struct ubuf_info	uarg;
-	unsigned long		account_pages;
+
+	unsigned		account_pages;
 	bool			zc_report;
 	bool			zc_used;
 	bool			zc_copied;