zsmalloc: reorganize struct size_class to pack 4 bytes hole

Reoder the pages_per_zspage field in struct size_class which can
eliminate the 4 bytes hole between it and stats field.

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -213,10 +213,10 @@ struct size_class {
 	int size;
 	unsigned int index;
 
-	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
-	int pages_per_zspage;
 	struct zs_size_stat stats;
 
+	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
+	int pages_per_zspage;
 	/* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
 	bool huge;
 };