Wrong index while dumping the print sub-system's state.

The wrong method was used when getting the user states to dump
and as a result only the state for the current user was dumped
as we get an exception for the other users.

bug:11457875

Change-Id: I9a3bcac01f1f1cf4f6e72aefff7cff2e0c6bca94

services/java/com/android/server/print/PrintManagerService.java

@@ -366,7 +366,7 @@ public final class PrintManagerService extends IPrintManager.Stub {
                 pw.println("PRINT MANAGER STATE (dumpsys print)");
                 final int userStateCount = mUserStates.size();
                 for (int i = 0; i < userStateCount; i++) {
-                    UserState userState = mUserStates.get(i);
+                    UserState userState = mUserStates.valueAt(i);
                     userState.dump(fd, pw, "");
                     pw.println();
                 }