mm/hugetlb.c: use helper macro K()

Use helper macro K() to improve code readability.  No functional
modification involved.

Link: https://lkml.kernel.org/r/20230804012559.2617515-8-zhangpeng362@huawei.comSigned-off-by: ZhangPeng <zhangpeng362@huawei.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/hugetlb.c

@@ -4748,7 +4748,7 @@ void hugetlb_show_meminfo_node(int nid)
 void hugetlb_report_usage(struct seq_file *m, struct mm_struct *mm)
 {
 	seq_printf(m, "HugetlbPages:\t%8lu kB\n",
-		   atomic_long_read(&mm->hugetlb_usage) << (PAGE_SHIFT - 10));
+		   K(atomic_long_read(&mm->hugetlb_usage)));
 }
 
 /* Return the number pages of memory we physically have, in PAGE_SIZE units. */