Make interface linkable for libmediadrm

Add build flag to fix aidl converted libmediadrm
link error.

Test: CtsMediaDrmTestCases, GtsMediaTestCases

Bug: 200055138
Bug: 170964303
Change-Id: Ifa0cfbb269e768dadf3ff69d7c0c2f17ad1eb540
diff --git a/drm/aidl/Android.bp b/drm/aidl/Android.bp
index d8500ec..1d97e80 100644
--- a/drm/aidl/Android.bp
+++ b/drm/aidl/Android.bp
@@ -29,4 +29,5 @@
             min_sdk_version: "current",
         },
     },
+    double_loadable: true,
 }