WallpaperManagerCompat should target correct platform

Also replace Utilities.isAtLeastO() to static final constant.
Bug: 65544683

Change-Id: I39fbea66939d72c31702748716c4e65b4f9bee6a

src/com/android/launcher3/graphics/DrawableFactory.java

@@ -80,7 +80,7 @@ public class DrawableFactory {
 
 
     protected Path getPreloadProgressPath(Context context) {
-        if (Utilities.isAtLeastO()) {
+        if (Utilities.ATLEAST_OREO) {
             try {
                 // Try to load the path from Mask Icon
                 Drawable icon = context.getDrawable(R.drawable.adaptive_icon_drawable_wrapper);