Make serde available to product and vendor

Bug: 270690570

Test: mma in external/rust/crates
Change-Id: If76b6141a49fbd5cfd24f1684fb8d4fcdb33de3e
diff --git a/Android.bp b/Android.bp
index a129ef0..d88ecc7 100644
--- a/Android.bp
+++ b/Android.bp
@@ -58,6 +58,7 @@
         "//apex_available:platform",
         "//apex_available:anyapex",
     ],
+    product_available: true,
     vendor_available: true,
     min_sdk_version: "29",
 }