tipc: use bash here string instead of echo

Use bash here string redirect instead of pipeing via echo when
processing raw link data.

completions/tipc

@@ -74,7 +74,7 @@ _tipc_link() {
         # awk drops link state and last trailing :
         local links=$(tipc link list | awk '{print substr($1, 0, length($1)-1)}')
         if [[ $filter == "peers" ]]; then
-            links=$(echo "$links" | sed '/broadcast-link/d')
+            links=$(sed '/broadcast-link/d' <<<"$links")
         fi
         COMPREPLY=( $( compgen -W '$links' -- $cur ) )
     fi