LU-9848 llog: check padding size for update reclen

LU-9848 llog: check padding size for update reclen

Update log only checks padding size for split case, which should also
be done if it's less than chunk size.

Signed-off-by: Lai Siyao <lai.siyao@intel.com>
Change-Id: Ie7819f67dd9bcbfb060713bb208c9777420c5178
Reviewed-on: https://review.whamcloud.com/28554
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: wangdi <di.wang@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>