zink: set compareEnable when setting compareOp

zink: set compareEnable when setting compareOp

We need to enable compareEnable for compareOp to be valid, and ANV was
recently updated to respect this. So let's update Zink to match.

This fixes the shadow-variants of several piglit regressions, like these:
spec@arb_shader_texture_lod@execution@tex-miplevel-selection
spec@glsl-1.20@execution@tex-miplevel-selection

Fixes: a19cdf989b1 ("anv: only use VkSamplerCreateInfo::compareOp if enabled")
Reviewed-by: Eric Engestrom <eric@engestrom.ch>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3473>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3473>