staging: lustre: mdt: add OBD_CONNECT_DIR_STRIPE flag

Add OBD_CONNECT_DIR_STRIPE to tell if the client supports
striped dir, so only new client (>= 2.6) can access striped
directory.

Signed-off-by: wang di <di.wang@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-4843
Reviewed-on: http://review.whamcloud.com/10773


Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>