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

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

Link: https://lkml.kernel.org/r/20230804012559.2617515-4-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/swap_state.c

@@ -63,9 +63,8 @@ static atomic_t swapin_readahead_hits = ATOMIC_INIT(4);
 void show_swap_cache_info(void)
 {
 	printk("%lu pages in swap cache\n", total_swapcache_pages());
-	printk("Free swap  = %ldkB\n",
-		get_nr_swap_pages() << (PAGE_SHIFT - 10));
-	printk("Total swap = %lukB\n", total_swap_pages << (PAGE_SHIFT - 10));
+	printk("Free swap  = %ldkB\n", K(get_nr_swap_pages()));
+	printk("Total swap = %lukB\n", K(total_swap_pages));
 }
 
 void *get_shadow_from_swap_cache(swp_entry_t entry)