anv: convert assert into unreachable to avoid fallthrough error

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/18192>

src/intel/vulkan/genX_state.c

@@ -869,7 +869,7 @@ vk_to_intel_tex_filter(VkFilter filter, bool anisotropyEnable)
 {
    switch (filter) {
    default:
-      assert(!"Invalid filter");
+      unreachable("Invalid filter");
    case VK_FILTER_NEAREST:
       return anisotropyEnable ? MAPFILTER_ANISOTROPIC : MAPFILTER_NEAREST;
    case VK_FILTER_LINEAR: