ceph: uninitialized variable in debug output

If read_mapping_folio() fails then "inline_version" is printed without
being initialized.

[ jlayton: use CEPH_INLINE_NONE instead of "-1" ]

Fixes: 083db6fd

 ("ceph: uninline the data on a file opened for writing")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>