Change libeffect from vendor:true to vendor_available:true

libaudioflinger is still using the lib in the aosp/master branch.

Bug: 33241851
Test: BOARD_VNDK_VERSION=current m -j
Merged-In: I11b54a5f050f914afc234e15f680581d15064c82
Change-Id: I9808ea87ea037a3caef03b2beabd1a717f153a6d
diff --git a/media/libeffects/factory/Android.bp b/media/libeffects/factory/Android.bp
index 16680bd..01554c2 100644
--- a/media/libeffects/factory/Android.bp
+++ b/media/libeffects/factory/Android.bp
@@ -9,7 +9,7 @@
 // Effect factory library
 cc_library_shared {
     name: "libeffects",
-    vendor: true,
+    vendor_available: true,
     srcs: ["EffectsFactory.c"],
 
     shared_libs: [