Remove module * parameter from class_create() (#222)

From v6.4, class_create() does not have module *
See commit 11ba11 :
> driver core: class: remove module * from class_create()
> 
> The module pointer in class_create() never actually did anything,
> and it shouldn't have been requred to be set as a parameter even
> if it did something.  So just remove it and fix up all callers of the
> function in the kernel tree at the same time.

examples/chardev.c

@@ -14,6 +14,7 @@
 #include <linux/printk.h>
 #include <linux/types.h>
 #include <linux/uaccess.h> /* for get_user and put_user */
+#include <linux/version.h>
 
 #include <asm/errno.h>
 
@@ -62,7 +63,11 @@ static int __init chardev_init(void)
 
     pr_info("I was assigned major number %d.\n", major);
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(6, 4, 0)
+    cls = class_create(DEVICE_NAME);
+#else
     cls = class_create(THIS_MODULE, DEVICE_NAME);
+#endif
     device_create(cls, NULL, MKDEV(major, 0), NULL, DEVICE_NAME);
 
     pr_info("Device created on /dev/%s\n", DEVICE_NAME);