LU-11369 hsm: allow non-owner writers to set HSM state dirty

LU-11369 hsm: allow non-owner writers to set HSM state dirty

In mdt_add_dirty_flag(), bump up the capability so that
mdt_hsm_attr_set() will succeed even if the writer (or truncater) is
not the owner of the file.

Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: Ibd7e9e039c3a984642b4a01c63cd11d2029e93f1
Reviewed-on: https://review.whamcloud.com/33158
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mike Pershin <mpershin@whamcloud.com>
Reviewed-by: Quentin Bouget <quentin.bouget@cea.fr>
Reviewed-by: Oleg Drokin <green@whamcloud.com>