mm/ksm: use helper macro __ATTR_RW

Use helper macro __ATTR_RW to define KSM_ATTR to make code more clear.
Minor readability improvement.

Link: https://lkml.kernel.org/r/20220221115809.26381-1-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/ksm.c

@@ -2829,8 +2829,7 @@ static void wait_while_offlining(void)
 #define KSM_ATTR_RO(_name) \
 	static struct kobj_attribute _name##_attr = __ATTR_RO(_name)
 #define KSM_ATTR(_name) \
-	static struct kobj_attribute _name##_attr = \
-		__ATTR(_name, 0644, _name##_show, _name##_store)
+	static struct kobj_attribute _name##_attr = __ATTR_RW(_name)
 
 static ssize_t sleep_millisecs_show(struct kobject *kobj,
 				    struct kobj_attribute *attr, char *buf)