Revert "libkeystore-wifi-hidl: Updated to vendor_available:true"

This reverts commit 64ce92520d2718c390bfa11de516cf9e1fd58ea2.

Reason for revert: 'vendor_available:true' is no longer required

Change-Id: I9430bc9744bf7af91bf9a0b7faf6e553c273d3b1
diff --git a/keystore/Android.bp b/keystore/Android.bp
index b59bacc..0ab5198 100644
--- a/keystore/Android.bp
+++ b/keystore/Android.bp
@@ -102,5 +102,5 @@
 
     export_include_dirs: ["include"],
 
-    vendor_available: true,
+    vendor: true,
 }