LU-17000 mgs: check lcfg parameters

LU-17000 mgs: check lcfg parameters

Check lcfg parameters in mgs_iocontrol() and mgs_iocontrol_pool().
Make the callers more consistent with buffer access and error checks.
REC_DATA_LEN() should be used instead of "rec_len" for lcfg size,
since "rec_len" is the full llog record size including hdr/tail.

CoverityID: 397130 ("Passing tainted expression lcfg->lcfg_buflens")
CoverityID: 397132 ("Passing tainted expression lcfg->lcfg_buflens")
CoverityID: 425252 ("Untrusted value as argument")

Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Change-Id: I9a7052a24d77124582df61340e520c1db6433892
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/58360
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>