ocfs2/cluster/netdebug.c: fix warning

fs/ocfs2/cluster/netdebug.c:154: warning: format '%lu' expects
     type 'long unsigned int', but argument 17 has type 'suseconds_t'
Signed-off-by: NAlexander Beregalov <a.beregalov@gmail.com>
Signed-off-by: NMark Fasheh <mfasheh@suse.com>