ceph: fscache: Update object store limit after file writing

Synchronize object->store_limit[_l] with new inode->i_size after file writing.

Tested-by: Milosz Tanski <milosz@adfin.com>
Signed-off-by: Yunchuan Wen <yunchuanwen@ubuntukylin.com>
Signed-off-by: Min Chen <minchen@ubuntukylin.com>
Signed-off-by: Li Wang <liwang@ubuntukylin.com>