Bluetooth: Mesh: Provisioner sample: Permit 16 nodes

Ups the CDB_NODE_COUNT config to fit 16 nodes, to make the sample more
usable for general mesh testing.

Signed-off-by: Trond Einar Snekvik <Trond.Einar.Snekvik@nordicsemi.no>
diff --git a/samples/bluetooth/mesh_provisioner/prj.conf b/samples/bluetooth/mesh_provisioner/prj.conf
index d097785..8c8e88d 100644
--- a/samples/bluetooth/mesh_provisioner/prj.conf
+++ b/samples/bluetooth/mesh_provisioner/prj.conf
@@ -27,7 +27,7 @@
 CONFIG_BT_MESH_PROVISIONER=y
 CONFIG_BT_MESH_PROV_DEVICE=n
 CONFIG_BT_MESH_CDB=y
-CONFIG_BT_MESH_CDB_NODE_COUNT=3
+CONFIG_BT_MESH_CDB_NODE_COUNT=16
 CONFIG_BT_MESH_CDB_SUBNET_COUNT=3
 CONFIG_BT_MESH_CDB_APP_KEY_COUNT=3