rename vpp-dpdk-dev to vpp-ext-deps

We need to have new tenants in the development package.
This is first of series of patches which will allow us to have multiple
external libs and tools packaged for developer's convenience.

Change-Id: I884bd75fba96005bbf8cea92774682b2228e0e22
Signed-off-by: Damjan Marion <damarion@cisco.com>

test/scripts/socket_test.sh

@@ -334,7 +334,7 @@ fi
 
 if [ -n "$multi_host"] && [ ! -f "$dpdk_devbind" ] ; then
     echo "ERROR: Can't find dpdk-devbind.py!"
-    echo "       Run \"cd \$WS_ROOT; make dpdk-install-dev\" to install it."
+    echo "       Run \"cd \$WS_ROOT; make install-ext-deps\" to install it."
     echo
     env_test_failed="true"
 fi