mm/damon: fix sparse warning for zero initializer

sparse warns about zero initializing an array with {0,}, change it to
the equivalent {0}.

Fixes the sparse warning:
mm/damon/tests/vaddr-kunit.h:69:47: warning: missing braces around initializer

Link: https://lkml.kernel.org/r/xriwklcwjpwcz7eiavo6f7envdar4jychhsk6sfkj5klaznb6b@j6vrvr2sxjht
Fixes: 17ccae8 ("mm/damon: add kunit tests")
Signed-off-by: Leo Stone <leocstone@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jinjie Ruan <ruanjinjie@huawei.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: leocstone

mm/damon/tests/vaddr-kunit.h

@@ -66,7 +66,7 @@ static int __link_vmas(struct maple_tree *mt, struct vm_area_struct *vmas,
 static void damon_test_three_regions_in_vmas(struct kunit *test)
 {
 	static struct mm_struct mm;
-	struct damon_addr_range regions[3] = {0,};
+	struct damon_addr_range regions[3] = {0};
 	/* 10-20-25, 200-210-220, 300-305, 307-330 */
 	struct vm_area_struct vmas[] = {
 		(struct vm_area_struct) {.vm_start = 10, .vm_end = 20},