Add manual support for macvlan networks to bash completion

Signed-off-by: Harald Albers <github@albersweb.de>
(cherry picked from commit 6c98d5bfaccda4b211e537f5072767160a20d497)
Signed-off-by: Tibor Vass <tibor@docker.com>

contrib/completion/bash/docker

@@ -1445,7 +1445,7 @@ _docker_network_create() {
 			return
 			;;
 		--driver|-d)
-			local plugins=" $(__docker_plugins Network) "
+			local plugins="$(__docker_plugins Network) macvlan"
 			# remove drivers that allow one instance only
 			plugins=${plugins/ host / }
 			plugins=${plugins/ null / }