Remove more internal fields from ModuleBase.

Bug: 358425833
Test: Manual compare the generated ninja and mk files and CI.
Change-Id: I4edd0dc646ac035594f47cd9044cc4eb5f710e64
diff --git a/filesystem/system_image.go b/filesystem/system_image.go
index 69d922d..a8fd368 100644
--- a/filesystem/system_image.go
+++ b/filesystem/system_image.go
@@ -61,7 +61,8 @@
 
 	deps := s.gatherFilteredPackagingSpecs(ctx)
 	ctx.WalkDeps(func(child, parent android.Module) bool {
-		for _, ps := range child.PackagingSpecs() {
+		for _, ps := range android.OtherModuleProviderOrDefault(
+			ctx, child, android.InstallFilesProvider).PackagingSpecs {
 			if _, ok := deps[ps.RelPathInPackage()]; ok {
 				modulesInPackageByModule[child] = true
 				modulesInPackageByName[child.Name()] = true