Fix print settings crash.

Bug: 25889661
Change-Id: I691b913ce0adc06c29c21ad12d979a0d0e3ad8e7
diff --git a/src/com/android/settings/print/PrintServiceSettingsFragment.java b/src/com/android/settings/print/PrintServiceSettingsFragment.java
index dd41323..f174614 100644
--- a/src/com/android/settings/print/PrintServiceSettingsFragment.java
+++ b/src/com/android/settings/print/PrintServiceSettingsFragment.java
@@ -378,7 +378,7 @@
 
                 @Override
                 public boolean onQueryTextChange(String searchString) {
-                    ((Filterable) getListView().getAdapter()).getFilter().filter(searchString);
+                    mPrintersAdapter.getFilter().filter(searchString);
                     return true;
                 }
             });