CP-7199: Enable detect_prio setting again

Now with package from CentOS 6.5 ALUA works correctly with this setting.

Signed-off-by: Frediano Ziglio <frediano.ziglio@citrix.com>
Reviewed-by: Robert Breker <robert.breker@citrix.com>
Acked-by: Vineeth Raveendran <vineeth.thampi@citrix.com>

GitHub: closes #76 on xapi-project/sm