Set prebuilt_apis java_imports sdk_version to none

Bug: 160455085
Test: m
Change-Id: I9057e68d7e01f0a339113383b92bfe860688bc7c
(cherry picked from commit 6b36db7c2541fc4f336bd1b134f4113071568481)
diff --git a/Android.bp b/Android.bp
index 4741c58..9b7e14b 100644
--- a/Android.bp
+++ b/Android.bp
@@ -124,4 +124,5 @@
         "30",
         "current",
     ],
+    imports_sdk_version: "none",
 }