LU-5113 osd: add striped dir feature flag to LMA

LU-5113 osd: add striped dir feature flag to LMA

Add striped directory feature flag(LMAI_STRIPED) to LMA, so
once MDS is downgraded, the striped directory will be accessed
by old lustre(< 2.6) on MDT.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I763217e3554dc4d68ee2f72d53c0e119fff6cbef
Reviewed-on: http://review.whamcloud.com/10463
Tested-by: Jenkins
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>