rak7289v2: Remove chirpstack-mqtt-forwarder-single.

This package should not be installed as this gateway already has the
-slot1 and -slot2 packages installed.

Author: brocaar

conf/rak_rak7289v2/.config

@@ -1815,7 +1815,7 @@ CONFIG_PACKAGE_chirpstack-concentratord-target-rak7289v2=y
 CONFIG_PACKAGE_chirpstack-gateway-mesh=y
 CONFIG_PACKAGE_chirpstack-mqtt-forwarder=y
 CONFIG_PACKAGE_chirpstack-mqtt-forwarder-mesh=y
-CONFIG_PACKAGE_chirpstack-mqtt-forwarder-single=y
+# CONFIG_PACKAGE_chirpstack-mqtt-forwarder-single is not set
 CONFIG_PACKAGE_chirpstack-mqtt-forwarder-slot1=y
 CONFIG_PACKAGE_chirpstack-mqtt-forwarder-slot2=y
 CONFIG_PACKAGE_chirpstack-udp-forwarder=y