Fix "natural scrolling"
Fix "natural scrolling"

> Movements down (scroll backward) generate negative y values and up
> (scroll forward) generate positive y values.

> If direction is SDL_MOUSEWHEEL_FLIPPED the values in x and y will be
> opposite. Multiply by -1 to change them back.

<https://wiki.libsdl.org/SDL_MouseWheelEvent#Remarks>

The x and y values already take the scrolling configuration into
account. Reversing the values when the direction is flipped cancels the
scrolling configuration.

Therefore, just ignore the direction field.

Fixes <https://github.com/Genymobile/scrcpy/issues/966>

Genymobile/scrcpy,Genymobile/scrcpy,Genymobile/scrcpy