MVKDevice: Clamp max per-set descriptor limit to minimum 1024.

[cdavis5e]

As required by the Vulkan spec.

Fixes the CTS tests
dEQP-VK.api.info.vulkan1p2_limits_validation.khr_maintenance_3 and
dEQP-VK.api.maintenance3_check.maintenance3_properties.

[billhollings]

This feels arbitrary. Unless arg buffers are in play, this minimum total is never going to be met.

Walk me through this. By inflating this value, what are we telling an app that might be dangerous?

[cdavis5e]

This feels arbitrary. Unless arg buffers are in play, this minimum total is never going to be met.

Walk me through this. By inflating this value, what are we telling an app that might be dangerous?

This is the maximum number of total descriptors of all types across all stages that may be contained in a descriptor set at once. It's meant to be a constraint on the size of a descriptor set itself. Even if we were to raise it, an app would still be constrained by the maximum per-type descriptor counts.

This is the minimum maximum that is mandated by the Vulkan spec. The CTS actually tests that the limit is at least 1024.