spirv/subgroups: Stop incrementing w

The w++ is to handle a differences between the KHR extension and Vulkan
1.1 feature where the Vulkan 1.1 instructions take an scope parameter.
While incrementing w technically works, it's really subtle and very easy
to miss when reading the code.

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5278>
1 file changed