EX-6127 llite: getting stripe info optimization

EX-6127 llite: getting stripe info optimization

ll_lov_getstripe_ea_info() is expensive call and should be avoided
if possible. Let's use cached chunk size rather than get it from
stripe info every time.

Signed-off-by: Artem Blagodarenko <ablagodarenko@ddn.com>
Change-Id: Id08487ec782f797e242e3f673c4a4dd8d526c9cc
Reviewed-on: https://review.whamcloud.com/c/ex/lustre-release/+/51321
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>