Fix google-explicit-constructor warnings in inputflinger.

* Add explicit keyword to conversion constructors.
Bug: 28341362
Test: build with WITH_TIDY=1

Change-Id: I8259317db74b177b6e62a0aa2ad21aead47f698e
diff --git a/services/inputflinger/host/InputDriver.h b/services/inputflinger/host/InputDriver.h
index 8d5a31e..e56673b 100644
--- a/services/inputflinger/host/InputDriver.h
+++ b/services/inputflinger/host/InputDriver.h
@@ -82,7 +82,7 @@
 
 class InputDriver : public InputDriverInterface {
 public:
-    InputDriver(const char* name);
+    explicit InputDriver(const char* name);
     virtual ~InputDriver() = default;
 
     virtual void init() override;