LU-18951 utils: validate ioc_inlbuf in llog_ioctl()

LU-18951 utils: validate ioc_inlbuf in llog_ioctl()

Validate that the inlbuf is initialized with the log index
for OBD_IOC_LLOG_CANCEL and similarly for other ioctl commands
in llog_ioctl().

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I237a4f6906dabd64aa2106b6917e9660a92540e5
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/59051
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Emoly Liu <emoly@whamcloud.com>
Reviewed-by: Manish Regmi <mregmi@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>