LU-6984 lmv: remove nlink check in lmv_revalidate_slaves

LU-6984 lmv: remove nlink check in lmv_revalidate_slaves

Remove nlink < 2 check in lmv_revalidate_slaves, because
after nlink reaches to LDISKFS_LINK_MAX (65000), the inode
nlink will be set to 1.

Add test_300o in sanity to verify the case.

And also add version check for striped dir test.

Test-Parameters: envdefinitions=SLOW=yes testlist=sanity
Change-Id: I1a333ea7f68da9157679c1358df5f7a54aee8e51
Signed-off-by: di wang <di.wang@intel.com>
Reviewed-on: http://review.whamcloud.com/16490
Tested-by: Jenkins
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Jian Yu <jian.yu@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>