LU-12678 socklnd: use list_for_each_entry_safe()

LU-12678 socklnd: use list_for_each_entry_safe()

Several loops use list_for_each_safe(), then call list_entry() as
first step.  These can be merged using list_for_each_entry_safe().

In one case, the 'safe' version is clearly not needed, so just use
list_for_each_entry().

Test-Parameters: trivial testlist=sanity-lnet
Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I52eb3598cf4308dfac0aad2a493c4b91c4102e7d
Reviewed-on: https://review.whamcloud.com/39129
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Chris Horn <chris.horn@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>