LU-12678 lnet: use list_first_entry() in lnet/klnds subdirectory.

LU-12678 lnet: use list_first_entry() in lnet/klnds subdirectory.

Convert
  list_entry(foo->next .....)
to
  list_first_entry(foo, ....)

in 'lnet/klnds

In several cases the call is combined with a list_empty() test and
list_first_entry_or_null() is used

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Mr. NeilBrown <neilb@suse.de>
Change-Id: I3b2b33c3c9284c02e44610614d64a1f84be300a4
Reviewed-on: https://review.whamcloud.com/43419
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>