kfifo: don't use "proxy" headers

Update header inclusions to follow IWYU (Include What You Use) principle.

Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Andy Shevchenko <[e-mail]>
Cc: Alain Volmat <[e-mail]>
Cc: AngeloGioacchino Del Regno <[e-mail]>
Cc: Chen-Yu Tsai <[e-mail]>
Cc: Hans Verkuil <[e-mail]>
Cc: Jernej Skrabec <[e-mail]>
Cc: Matthias Brugger <[e-mail]>
Cc: Mauro Carvalho Chehab <[e-mail]>
Cc: Patrice Chotard <[e-mail]>
Cc: Rob Herring <[e-mail]>
Cc: Samuel Holland <[e-mail]>
Cc: Sean Wang <[e-mail]>
Cc: Sean Young <[e-mail]>
Cc: Stefani Seibold <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>

include/linux/kfifo.h

···
  * to lock the reader.
  */
 
-#include <linux/kernel.h>
+#include <linux/array_size.h>
 #include <linux/spinlock.h>
 #include <linux/stddef.h>
-#include <linux/scatterlist.h>
+#include <linux/types.h>
+
+#include <asm/barrier.h>
+#include <asm/errno.h>
+
+struct scatterlist;
 
 struct __kfifo {
 	unsigned int	in;

lib/kfifo.c

···
  * Copyright (C) 2009/2010 Stefani Seibold <[e-mail]>
  */
 
-#include <linux/kernel.h>
-#include <linux/export.h>
-#include <linux/slab.h>
 #include <linux/err.h>
-#include <linux/log2.h>
-#include <linux/uaccess.h>
+#include <linux/export.h>
 #include <linux/kfifo.h>
+#include <linux/log2.h>
+#include <linux/scatterlist.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
 
 /*
  * internal helper to calculate the unused elements in a fifo

samples/kfifo/dma-example.c

···
  */
 
 #include <linux/init.h>
-#include <linux/module.h>
 #include <linux/kfifo.h>
+#include <linux/module.h>
+#include <linux/scatterlist.h>
 
 /*
  * This module shows how to handle fifo dma operations.