zink: handle NULL views in zink_set_sampler_views

Passing NULL for the views parameter should be the same as passing an
array of NULL, according to the documentation. So let's respect that
detail.

This fixes a crash when using GALLIUM_HUD.

Fixes: 8d46e35d16e ("zink: introduce opengl over vulkan")
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8564>
(cherry picked from commit 333730405de28153f2378d498e45cb82024fc230)
2 files changed