Fix a NPE when highlighting fingerprint row.

If fingerprint pref is not bound to UI yet, then its view is null so we
can't do any ripple animation on it.

Change-Id: I0ccca2dfdb471ab520677c6cd206205230959b27
Fixes: 80147956
Test: manual

src/com/android/settings/fingerprint/FingerprintSettings.java

@@ -605,6 +605,10 @@ public class FingerprintSettings extends SubSettings {
             final Drawable highlight = getHighlightDrawable();
             if (highlight != null && fpref != null) {
                 final View view = fpref.getView();
+                if (view == null) {
+                    // FingerprintPreference is not bound to UI yet, so view is null.
+                    return;
+                }
                 final int centerX = view.getWidth() / 2;
                 final int centerY = view.getHeight() / 2;
                 highlight.setHotspot(centerX, centerY);