InputMapper refactor: Change readerconfig pointer to const ref

We are refactoring Input-mapper to ensure they are configured at the
time of initialisation.

In this CL we are changing InputReaderConfiguration raw pointer to
a const reference and rename it to readerConfig for clarity.

Test: build, inputflinger_tests, presubmit checks

Bug: 256009910
Change-Id: Iae22c8cfba836bd311a51fca13d680456a61e604
diff --git a/services/inputflinger/reader/mapper/JoystickInputMapper.h b/services/inputflinger/reader/mapper/JoystickInputMapper.h
index 9adb07f..6f1c6b7 100644
--- a/services/inputflinger/reader/mapper/JoystickInputMapper.h
+++ b/services/inputflinger/reader/mapper/JoystickInputMapper.h
@@ -29,7 +29,7 @@
     virtual void populateDeviceInfo(InputDeviceInfo& deviceInfo) override;
     virtual void dump(std::string& dump) override;
     [[nodiscard]] std::list<NotifyArgs> reconfigure(nsecs_t when,
-                                                    const InputReaderConfiguration* config,
+                                                    const InputReaderConfiguration& config,
                                                     uint32_t changes) override;
     [[nodiscard]] std::list<NotifyArgs> reset(nsecs_t when) override;
     [[nodiscard]] std::list<NotifyArgs> process(const RawEvent* rawEvent) override;