ceph/mds_client.c: quiet sparse noise

Quiet the following sparse noise:

warning: symbol 'get_nonsnap_parent' was not declared. Should it be static?
warning: symbol 'done_closing_sessions' was not declared. Should it be static?

Local functions don't need external visability. Make them static.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Sage Weil <sage@newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>