mm/damon/sysfs: remove parameters of damon_sysfs_region_alloc()

'damon_sysfs_region_alloc()' is always called with zero-filled 'struct
damon_addr_range', because the start and end addresses should set by
users.  Remove unnecessary parameters of the function and simplify the
body by using 'kzalloc()'.

Link: https://lkml.kernel.org/r/20221026225943.100429-7-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/sysfs.c

@@ -1065,17 +1065,9 @@ struct damon_sysfs_region {
 	struct damon_addr_range ar;
 };
 
-static struct damon_sysfs_region *damon_sysfs_region_alloc(
-		struct damon_addr_range ar)
+static struct damon_sysfs_region *damon_sysfs_region_alloc(void)
 {
-	struct damon_sysfs_region *region = kmalloc(sizeof(*region),
-			GFP_KERNEL);
-
-	if (!region)
-		return NULL;
-	region->kobj = (struct kobject){};
-	region->ar = ar;
-	return region;
+	return kzalloc(sizeof(struct damon_sysfs_region), GFP_KERNEL);
 }
 
 static ssize_t start_show(struct kobject *kobj, struct kobj_attribute *attr,
@@ -1184,7 +1176,7 @@ static int damon_sysfs_regions_add_dirs(struct damon_sysfs_regions *regions,
 	regions->regions_arr = regions_arr;
 
 	for (i = 0; i < nr_regions; i++) {
-		region = damon_sysfs_region_alloc((struct damon_addr_range){});
+		region = damon_sysfs_region_alloc();
 		if (!region) {
 			damon_sysfs_regions_rm_dirs(regions);
 			return -ENOMEM;