LU-9633 llite: Add kernel doc style for lustre/llite/*.c (Part 5)

LU-9633 llite: Add kernel doc style for lustre/llite/*.c (Part 5)

This patch converts existing functional comments
to kernel doc style comments and removes '/**' for
comments which is not meant to be a kernel-doc comment

Tested:
./kernel-doc -v -none lustre/llite/namei.c lustre/llite/lproc_llite.c
llite/namei.c:101: info: Scanning doc for function ll_iget
llite/namei.c:1299: info: Scanning doc for function ll_atomic_open
llite/lproc_llite.c:83: info: Scanning doc for function ll_stats_pid_write
llite/lproc_llite.c:1355: info: Scanning doc for function default_easize_show
llite/lproc_llite.c:1383: info: Scanning doc for function default_easize_store

Test-Parameters: trivial
Signed-off-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Change-Id: I8178ca5c2605341f13e307ef5e194f2b4ba8a5bd
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58277
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Petros Koutoupis <petros.koutoupis@hpe.com>
Reviewed-by: Anjus George <georgea@ornl.gov>
Reviewed-by: Oleg Drokin <green@whamcloud.com>