hugetlbfs: fix hugetlbfs_statfs() locking

hugetlbfs: fix hugetlbfs_statfs() locking

[ Upstream commit 4b25f030ae69ba710eff587cabb4c57cb7e7a8a1 ]

After commit db71ef79b59b ("hugetlb: make free_huge_page irq safe"), the
subpool lock should be locked with spin_lock_irq() and all call sites was
modified as such, except for the ones in hugetlbfs_statfs().

Link: https://lkml.kernel.org/r/20220429202207.3045-1-almasrymina@google.com
Fixes: db71ef79b59b ("hugetlb: make free_huge_page irq safe")
Signed-off-by: Mina Almasry <almasrymina@google.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>