dlmglue.c: add missed mlog lines

This patch adds the missed mlog_exit() and mlog_exit_void() lines when routines
return.

Signed-off-by: Coly Li <coly.li@suse.de>
Acked-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>