Add a file node "page_pool_info" for debugfs, then cat this
file node to dump page pool info as below:

QUEUE_ID  ALLOCATE_CNT  FREE_CNT      POOL_SIZE(PAGE_NUM)  ORDER  NUMA_ID  MAX_LEN
0         512           0             512                  0      2        4K
1         512           0             512                  0      2        4K
2         512           0             512                  0      2        4K
3         512           0             512                  0      2        4K
4         512           0             512                  0      2        4K

Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>