Fix trailing garbage after UCS-2 encoded strings in ID3 V2.

related-to-bug: 2381919
diff --git a/media/libstagefright/id3/ID3.cpp b/media/libstagefright/id3/ID3.cpp
index 0547978..6d64717 100644
--- a/media/libstagefright/id3/ID3.cpp
+++ b/media/libstagefright/id3/ID3.cpp
@@ -335,7 +335,8 @@
         convertISO8859ToString8(mFrameData + 1, n, id);
     } else {
         // UCS-2
-        id->setTo((const char16_t *)(mFrameData + 1), n);
+        // API wants number of characters, not number of bytes...
+        id->setTo((const char16_t *)(mFrameData + 1), n / 2);
     }
 }