Remove llndk_headers module

Use a cc_library_headers module with llndk.llndk_headers: true instead
of an llndk_headers module.

Bug: 170784825
Test: m checkbuild
Test: compare out/soong/build.ninja
Change-Id: I063f695e2d02357cd7c66bd85c58a565485911f4
diff --git a/Android.bp b/Android.bp
index 06e9ee3..34dbbc3 100644
--- a/Android.bp
+++ b/Android.bp
@@ -71,13 +71,9 @@
         "//apex_available:platform",
         "com.android.virt",
     ],
-}
-
-// This module makes Vulkan headers available to vendor code that is
-// restricted to LLNDK dependencies.
-llndk_headers {
-    name: "vulkan_headers_llndk",
-    export_include_dirs: ["include"],
+    llndk: {
+        llndk_headers: true,
+    },
 }
 
 // This module makes Vulkan XML file available to vendor code.