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

After commit c22198e78d52 ("direct-io: remove random prefetches"), Nothing
in this file needs anything from `linux/prefetch.h`.

Signed-off-by: Youling Tang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Reviewed-by: Jan Kara <[e-mail]>
Signed-off-by: Christian Brauner <[e-mail]>

fs/direct-io.c

···
 #include <linux/rwsem.h>
 #include <linux/uio.h>
 #include <linux/atomic.h>
-#include <linux/prefetch.h>
 
 #include "internal.h"
 
···
 	struct buffer_head map_bh = { 0, };
 	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)