LU-5889 mdc: Proper accessing struct lov_user_md

LU-5889 mdc: Proper accessing struct lov_user_md

In mdc_setattr_pack() access the members of struct lov_user_md by
little endian byte order.

Signed-off-by: Yoshifumi Uemura <kogexe@gmail.com>
Change-Id: I201f00f527242faa6e1a199d3e792e5cdfa48006
Reviewed-on: http://review.whamcloud.com/12683
Tested-by: Jenkins
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>