LU-18110 doc: fix wrong structure name in llapi_advise

LU-18110 doc: fix wrong structure name in llapi_advise

lla_advice is misspelled as lla_ladvice in description,
so fix it.

Test-Parameters: trivial
Change-Id: I0ee455c5151436e3de114767fe3cfb6c164e6ef2
Signed-off-by: Oleg Drokin <green@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55967
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Frederick Dilger <fdilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>