Fix division by zero error in soft_max vulkan shader

This PR fixes #2596 by adding a check for p.KY being zero in the soft_max compute shader.

Changes:

• Modified the calculation of rowy in soft_max.comp to handle the case where p.KY is 0
• Changed const uint rowy = rowx % p.KY; to const uint rowy = (p.KY > 0) ? (rowx % p.KY) : 0;

The original code would cause a division by zero error when p.KY is 0. This fix ensures that rowy is set to 0 in such cases, preventing the crash while maintaining the expected behavior in normal scenarios.

Testing:

• Confirmed the fix resolves the crash in my environment
• Existing functionality remains unchanged when p.KY > 0