LU-9127 target: tgt_cb_last_committed is too noisy

LU-9127 target: tgt_cb_last_committed is too noisy

tgt_cb_last_committed() prints a D_HA message even if
last_committed was not updated. We can only print a
message when last_committed was updated, so we have
mostly the same information and save some debug log
space and cpu resource.

Change-Id: Ic2784e6a3652ca1851cde1313d6985ed2f90e36b
Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Reviewed-on: https://review.whamcloud.com/25469
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Alexander Boyko <alexander.boyko@seagate.com>
Reviewed-by: Alexander Zarochentsev <alexander.zarochentsev@seagate.com>
Reviewed-by: Alex Zhuravlev <alexey.zhuravlev@intel.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>