Specify product_specific property in adb_keys

The module installs the output file in product partition. This change
allows Soong to recognize it.

Test: m soong_generated_product_filesystem_test
Bug: 376515714
Change-Id: Idce4ac4974ea0331caf1f13f42e0dd57e0ec73d8
diff --git a/target/product/security/Android.bp b/target/product/security/Android.bp
index 69d19a3..ffbec06 100644
--- a/target/product/security/Android.bp
+++ b/target/product/security/Android.bp
@@ -40,4 +40,5 @@
 
 adb_keys {
     name: "adb_keys",
+    product_specific: true,
 }