MDS.cc: remove double is_clientreplay() check in active_start()

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Merge pull request #152 from dalgaaf/wip-da-fix-misc

MDS.cc: remove double is_clientreplay() check in active_start()

Reviewed-by: Sage Weil <sage@inktank.com>