anv: put parenthesis to the set_sampler_size equation

This fixes errors seen with some renderdoc captures failing to allocate
descriptor sets.

Fixes: 76096d04bba ("anv: relax restriction on variable count descriptors")
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Rohan Garg <rohan.garg@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34671>
1 file changed