Use consistent logical ID for joystick registration log

Just came across with an inconsistent numbering of logical IDs showed up for joystick registration log. It would be trivial but still confusing.

```
Joystick mapping: Logical id 1: USB,2-axis 8-button gamepad
Joystick mapping: Logical id 2: STICK A
Joystick: Start initialization
Input: Adding Joy #0: USB,2-axis 8-button gamepad
Joystick: USB,2-axis 8-button gamepad
Joystick:   ...  2 axes, 8 buttons 0 hats 0 balls
Joystick:   ...  Physical id 0 mapped to logical id 0
Input: Adding Joy #1: STICK A
Joystick: STICK A
Joystick:   ...  4 axes, 13 buttons 1 hats 0 balls
Joystick:   ...  Physical id 1 mapped to logical id 1
```

It's found while reporting [another SDL issue](https://bugzilla.libsdl.org/show_bug.cgi?id=2822) about registering joysticks on OS X.