third_party/linux: enable VLAN interface support

This is configurable through the Metropolis static network
configuration and thus needs to be enabled.

Change-Id: Id479e0d26a93819de0e315c8c470e94386f0351f
Reviewed-on: https://review.monogon.dev/c/monogon/+/2041
Tested-by: Jenkins CI
Reviewed-by: Leopold Schabel <leo@monogon.tech>
diff --git a/third_party/linux/linux-metropolis.config b/third_party/linux/linux-metropolis.config
index 1e5e1ab..3c05f85 100644
--- a/third_party/linux/linux-metropolis.config
+++ b/third_party/linux/linux-metropolis.config
@@ -1151,7 +1151,7 @@
 # CONFIG_BRIDGE_MRP is not set
 # CONFIG_BRIDGE_CFM is not set
 # CONFIG_NET_DSA is not set
-# CONFIG_VLAN_8021Q is not set
+CONFIG_VLAN_8021Q=y
 # CONFIG_DECNET is not set
 CONFIG_LLC=y
 # CONFIG_LLC2 is not set