Mark InputDispatcher::dump as const

This helps debug InputDispatcher by dumping its state from other const functions.

Bug: 281806933
Test: none
Change-Id: Ic7f1cef7eeaa753115143756ce60f4167412ef24
diff --git a/services/inputflinger/dispatcher/InputDispatcher.h b/services/inputflinger/dispatcher/InputDispatcher.h
index 37f569e..2b8b37e 100644
--- a/services/inputflinger/dispatcher/InputDispatcher.h
+++ b/services/inputflinger/dispatcher/InputDispatcher.h
@@ -87,7 +87,7 @@
                              std::chrono::nanoseconds staleEventTimeout);
     ~InputDispatcher() override;
 
-    void dump(std::string& dump) override;
+    void dump(std::string& dump) const override;
     void monitor() override;
     bool waitForIdle() const override;
     status_t start() override;