ceph: update cap message struct version to 10

The userland ceph has MClientCaps at struct version 10. This brings the
kernel up the same version.

For now, all of the the new stuff is set to default values including
the flags field, which will be conditionally set in a later patch.

Note that we don't need to set the change_attr and btime to anything
since we aren't currently setting the feature flag. The MDS should
ignore those values.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Reviewed-by: Yan, Zheng <zyan@redhat.com>