Convert libradio to Android.bp

See build/soong/README.md for more information.

Test: m -j checkbuild
Change-Id: If9daee8fea744a5d70cf0ea6efb2a806b6cffa36
diff --git a/Android.bp b/Android.bp
index 52cdada..69ed334 100644
--- a/Android.bp
+++ b/Android.bp
@@ -17,5 +17,6 @@
 subdirs = [
     "camera/ndk",
     "media/*",
+    "radio",
     "soundtrigger",
 ]