LU-16549 osp: Fix sizeof for RMF_OUT_UPDATE_HEADER

LU-16549 osp: Fix sizeof for RMF_OUT_UPDATE_HEADER

The first struct packed is actually a struct
out_update_header with no inline data, so it must be
packed in the size of out_update_header struct, but
gets packed as length 120 because of the size of struct
osp_update_request(which should never go over the wire).

Signed-off-by: Vitaliy Kuznetsov <vkuznetsov@ddn.com>
Change-Id: I692461ddf0493727e2dea222b6721c952d3166a1
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/50224
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Mikhail Pershin <mpershin@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>