initramfs: redirect 'ip route' output to null (#525)

this silences the spurious "ipv4: FIB table does not exist" error

Author: natthias

src/initramfs-tools/scripts/local-bottom/clevis.in

@@ -58,6 +58,6 @@ for iface in /sys/class/net/*; do
         iface=$(basename "$iface")
         ip link  set   dev "$iface" down
         ip addr  flush dev "$iface"
-        ip route flush dev "$iface"
+        ip route flush dev "$iface" > /dev/null 2>&1
     fi
 done