net: hns3: fix one incorrect value of page pool info when queried by debugfs

mainline inclusion
from mainline-v5.16-rc3
commit 9c147917
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I4M1HB
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9c1479174870



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Currently, when user queries page pool info by debugfs command
"cat page_pool_info", the cnt of allocated page for page pool may be
incorrect because of memory inconsistency problem caused by compiler
optimization.

So this patch uses READ_ONCE() to read value of pages_state_hold_cnt to
fix this problem.

Fixes: 850bfb91 ("net: hns3: debugfs add support dumping page pool info")
Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Yongxin Li <liyongxin1@huawei.com>
Signed-off-by: Junxin Chen <chenjunxin1@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>