Add a missing return.

Change Ic3d3ee6f3cccfcbe86996b67543fc5fdc64c85aa removed this return.

Bug: 179336328
Test: atest UpdatableSystemFontTest
Change-Id: Ibe6cdb67279fd34093ed9d6bb29376bd2eee0170

services/core/java/com/android/server/graphics/fonts/FontManagerService.java

@@ -345,6 +345,7 @@ public final class FontManagerService extends IFontManager.Stub {
             synchronized (mSerializedFontMapLock) {
                 mSerializedFontMap = serializeFontMap;
             }
+            return;
         } catch (IOException | ErrnoException e) {
             Slog.w(TAG, "Failed to serialize updatable font map. "
                     + "Retrying with system image fonts.", e);