Convert Visit*Deps from blueprint.Module to android.Module

Also adds checks that the dependencies are android.Modules and
are not disabled.

Test: m checkbuild
Change-Id: I05e945f38915d49cd3c0ab72a86576949bc7eff2
diff --git a/android/defaults.go b/android/defaults.go
index 4bf872e..c704529 100644
--- a/android/defaults.go
+++ b/android/defaults.go
@@ -131,7 +131,7 @@
 func defaultsMutator(ctx TopDownMutatorContext) {
 	if defaultable, ok := ctx.Module().(Defaultable); ok && len(defaultable.defaults().Defaults) > 0 {
 		var defaultsList []Defaults
-		ctx.WalkDeps(func(module, parent blueprint.Module) bool {
+		ctx.WalkDeps(func(module, parent Module) bool {
 			if ctx.OtherModuleDependencyTag(module) == DefaultsDepTag {
 				if defaults, ok := module.(Defaults); ok {
 					defaultsList = append(defaultsList, defaults)