m/node: remove non-definition dependencies

This enables usage from arbitrary platforms without including lots of
dependencies that aren't related to functionality.

Change-Id: I33e16b5396dc7216b676b294b8c1752caf3551b3
Reviewed-on: https://review.monogon.dev/c/monogon/+/3697
Tested-by: Jenkins CI
Vouch-Run-CI: Lorenz Brun <lorenz@monogon.tech>
Reviewed-by: Lorenz Brun <lorenz@monogon.tech>
diff --git a/metropolis/node/net_protocols.go b/metropolis/node/net_protocols.go
index ac43cbf..2e005fb 100644
--- a/metropolis/node/net_protocols.go
+++ b/metropolis/node/net_protocols.go
@@ -1,11 +1,9 @@
 package node
 
-import "github.com/vishvananda/netlink"
-
 // These are netlink protocol numbers used internally for various netlink
 // resource (e.g. route) owners/manager.
 const (
 	// ProtocolClusternet is used by //metropolis/node/core/clusternet when
 	// creating/removing routes pointing to the clusternet interface.
-	ProtocolClusternet netlink.RouteProtocol = 129
+	ProtocolClusternet int = 129
 )