fs/direct-io: Remove linux/prefetch.h include

After commit c22198e7 ("direct-io: remove random prefetches"), Nothing
in this file needs anything from `linux/prefetch.h`.
Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Link: https://lore.kernel.org/r/20240603014834.45294-1-youling.tang@linux.devReviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>

fs/direct-io.c

@@ -37,7 +37,6 @@
 #include <linux/rwsem.h>
 #include <linux/uio.h>
 #include <linux/atomic.h>
-#include <linux/prefetch.h>
 
 #include "internal.h"
 
@@ -1121,11 +1120,6 @@ ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
 	struct blk_plug plug;
 	unsigned long align = offset | iov_iter_alignment(iter);
 
-	/*
-	 * Avoid references to bdev if not absolutely needed to give
-	 * the early prefetch in the caller enough time.
-	 */
-
 	/* watch out for a 0 len io from a tricksy fs */
 	if (iov_iter_rw(iter) == READ && !count)
 		return 0;