backported_fixes_proto: specify sdk_version

backported_fixes_proto target requires sdk_version
to be specified. Specifying the current SDK.

Change-Id: I0266553b0e6d4cd8dba4ffa383b29040569637e1
Test: atest CtsOsTestCases
Bug: 384663328
diff --git a/backported_fixes/Android.bp b/backported_fixes/Android.bp
index 243e77e..0caea56 100644
--- a/backported_fixes/Android.bp
+++ b/backported_fixes/Android.bp
@@ -38,6 +38,7 @@
     name: "backported_fixes_proto",
     srcs: ["backported_fixes.proto"],
     host_supported: true,
+    sdk_version: "current",
 }
 
 java_library {