Update SignalDrawable to show X for empty state

The empty state is (enabled, but not connected).

TOOD: hide this icon from the status bar for single sim devices

Change-Id: I29afaf19f84740ab2df1bfe79a8f6f4a709e91ff
Fixes: 117671260
Test: visual
diff --git a/packages/SettingsLib/src/com/android/settingslib/graph/SignalDrawable.java b/packages/SettingsLib/src/com/android/settingslib/graph/SignalDrawable.java
index cb0b7c2..98eb573 100644
--- a/packages/SettingsLib/src/com/android/settingslib/graph/SignalDrawable.java
+++ b/packages/SettingsLib/src/com/android/settingslib/graph/SignalDrawable.java
@@ -286,8 +286,7 @@
 
     /** Returns the state representing empty mobile signal with the given number of levels. */
     public static int getEmptyState(int numLevels) {
-        // TODO empty state == 0 state. does there need to be a new drawable for this?
-        return getState(0, numLevels, false);
+        return getState(0, numLevels, true);
     }
 
     /** Returns the state representing carrier change with the given number of levels. */