LU-6341 llite: Use ll_dir_getstripe to get default LMVEA

LU-6341 llite: Use ll_dir_getstripe to get default LMVEA

Use ll_dir_getstripe to get default stripeEA in ll_new_node(),
Because ll_getxattr_common requires admin rights for retrieving
default LMVEA (because of trusted- prefix), which might cause
mkdir (from normal user) failure.

If parent does not have default stripeEA, then child should always
be in the same MDT for mkdir. Otherwise MDT should return -EREMOTE,
then client will refresh the default stripe index, and recreate
the object.

Signed-off-by: wang di <di.wang@intel.com>
Change-Id: I0d8884b78fbc8b8d1930b1133150686e65d20c54
Reviewed-on: http://review.whamcloud.com/13990
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>