counter: Cleanup lingering atomic.h includes

With the removal of the chrdev_lock atomic flag, the counter-sysfs.c and
counter-chrdev.c no longer needs to include the atomic.h header file.
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Link: https://lore.kernel.org/r/20211021103514.955622-1-vilhelm.gray@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/counter/counter-chrdev.c

@@ -3,7 +3,6 @@
  * Generic Counter character device interface
  * Copyright (C) 2020 William Breathitt Gray
  */
-#include <linux/atomic.h>
 #include <linux/cdev.h>
 #include <linux/counter.h>
 #include <linux/err.h>

drivers/counter/counter-sysfs.c

@@ -3,7 +3,6 @@
  * Generic Counter sysfs interface
  * Copyright (C) 2020 William Breathitt Gray
  */
-#include <linux/atomic.h>
 #include <linux/counter.h>
 #include <linux/device.h>
 #include <linux/err.h>