[PATCH v3 2/2] staging: iio: addac: adt7316: replace kernel.h with explicit headers

[Abdelnasser Hussein <abdelnasserhussein11@gmail.com>]

Drop the proxy header <linux/kernel.h> and replace it with direct
inclusions per the Include What You Use (IWYU) principle. Also remove
unused headers and keep the list alphabetically sorted.

Explicitly add:
- <linux/bits.h> for BIT()
- <linux/err.h> for IS_ERR() and PTR_ERR()
- <linux/errno.h> for error codes (-EIO, -EPERM, -EINVAL, -ENOMEM,
  -ENODEV)
- <linux/kstrtox.h> for kstrtou8(), kstrtou16(), and kstrtoint()
- <linux/pm.h> for EXPORT_GPL_SIMPLE_DEV_PM_OPS()
- <linux/string.h> for memcmp()
- <linux/types.h> for fixed-width and standard types (u8, u16, bool, s64)

Drop unused headers:
- <linux/i2c.h> (no I2C symbols used in core driver)
- <linux/kernel.h> (proxy header)
- <linux/list.h> (no linked list symbols used)
- <linux/rtc.h> (no RTC symbols used)
- <linux/slab.h> (no kmalloc/kfree symbols used)
- <linux/workqueue.h> (no workqueue symbols used)

Signed-off-by: Abdelnasser Hussein <abdelnasserhussein11@gmail.com>
---
v3:
 - Replace <linux/kernel.h> and add/remove headers in this patch, as
   suggested by Joshua Crofts.
 - Explicitly add <linux/err.h>, <linux/errno.h>, and <linux/types.h>
   per IWYU after symbol verification.
v2:
 - Split from original monolithic patch.

 drivers/staging/iio/addac/adt7316.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/drivers/staging/iio/addac/adt7316.c b/drivers/staging/iio/addac/adt7316.c
index 515f1fdae46b..54d942cae586 100644
--- a/drivers/staging/iio/addac/adt7316.c
+++ b/drivers/staging/iio/addac/adt7316.c
@@ -5,18 +5,19 @@
  * Copyright 2010 Analog Devices Inc.
  */
 
+#include <linux/bits.h>
 #include <linux/device.h>
+#include <linux/err.h>
+#include <linux/errno.h>
 #include <linux/gpio/consumer.h>
-#include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
-#include <linux/kernel.h>
-#include <linux/list.h>
+#include <linux/kstrtox.h>
 #include <linux/module.h>
-#include <linux/rtc.h>
-#include <linux/slab.h>
+#include <linux/pm.h>
+#include <linux/string.h>
 #include <linux/sysfs.h>
-#include <linux/workqueue.h>
+#include <linux/types.h>
 
 #include <linux/iio/events.h>
 #include <linux/iio/iio.h>
-- 
2.56.0