LU-12545 llite: cleanup stats of LPROC_LL_*

LU-12545 llite: cleanup stats of LPROC_LL_*

Some LPROC_LL_ stats are not used for a long time. This patch
removes them. LPROC_LL_STAFS is changed to LPROC_LL_STATFS in
this patch too.

Change-Id: I64b033e186733147e2a2984d8afec97240d03573
Signed-off-by: Li Xi <lixi@ddn.com>
Reviewed-on: https://review.whamcloud.com/35514
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>