Fix gamepad HID descriptor

Use Z and Rz for L2/R2, which are more widely supported than
Brake/Accelerator.

The right stick must then be bound to Rx and Ry.

Fixes #5362 <https://github.com/Genymobile/scrcpy/issues/5362>
PR #5623 <https://github.com/Genymobile/scrcpy/pull/5623>