zink: correct typo in stencil-setup

Without this, we end up using two-sided stencil when one-sided stencil
should be used. Whoops.

Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6853>
1 file changed