wayland-cursor: Use nominal size to calculate cursor scaling
This fixes the issue of giant cursors on KDE Wayland, when using a cursor theme where the cursor image size isn't equal to the nominal size (e.g. Breeze of KDE, Pop of System76). where image is 32x32 for nominal size 24.
Example: (KDE Plasma 6.1, Wayland, Breeze cursor size 24, 2.5x scaling)
Edited by Jin Liu