kernel/modules: relocate teql hotplug from iproute2 to kmod-sched

The link equalizer sch_teql.ko of package kmod-sched relies on a hotplug
script historically included in iproute2's tc package. In previous
discussion [1], consensus was the hotplug script is best located together
with the module in kmod-sched, but this change was deferred at the time.

Relocate the hotplug script now. This change also simplifies adding a tc
variant for minimal size with reduced functionality.

[1] https://github.com/openwrt/openwrt/pull/1627#issuecomment-447923636

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>
(cherry picked from commit 863ce4f15f)

package/kernel/linux/files/hotplug-sched-teql.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+. /lib/functions.sh
+
+if [ "$ACTION" != "ifup" ]; then
+	exit
+fi
+
+config_load network
+
+config_get teql $INTERFACE teql
+
+if [ "$teql" != "" ]; then
+    logger Adding device $DEVICE to TEQL master $teql
+    insmod sch_teql
+    tc qdisc add dev $DEVICE root $teql
+
+    # The kernel doesn't let us bring it up until it has at least one
+    # slave. So bring it up now, if it isn't already.
+    if ! cat /sys/class/net/$teql/carrier &>/dev/null; then
+        ifup $teql &
+    fi
+fi

package/kernel/linux/modules/netsupport.mk

@@ -916,6 +916,13 @@ define KernelPackage/sched/description
  Extra kernel schedulers modules for IP traffic
 endef
 
+SCHED_TEQL_HOTPLUG:=hotplug-sched-teql.sh
+
+define KernelPackage/sched/install
+	$(INSTALL_DIR) $(1)/etc/hotplug.d/iface
+	$(INSTALL_DATA) ./files/$(SCHED_TEQL_HOTPLUG) $(1)/etc/hotplug.d/iface/15-teql
+endef
+
 $(eval $(call KernelPackage,sched))