ceph: simply ceph_fh_to_dentry()

MDS handles LOOKUPHASH and LOOKUPINO MDS requests in the same way.
So __cfh_to_dentry() is redundant.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
ceph: fix ceph_fh_to_parent()

ceph_fh_to_parent() finds the inode that corresponds to the 'ino' field
of struct ceph_nfs_confh. This is wrong, it should find the inode that
corresponds to the 'parent_ino' field.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
ceph: add get_parent() callback for export_operations

The callback uses LOOKUPPARENT MDS request to find parent.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
ceph: print inode number for LOOKUPINO/LOOKUPPARENT request

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>