zink: set is_xfb=false for all i/o variables

this can affect streamout generation, even though it so far hasn't

cc: mesa-stable

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/24950>

src/gallium/drivers/zink/zink_compiler.c

@@ -5280,7 +5280,6 @@ zink_shader_create(struct zink_screen *screen, struct nir_shader *nir)
       var->data.is_xfb = false;
       if (glsl_type_is_image(var->type) || glsl_type_is_sampler(var->type)) {
          has_bindless_io = true;
-         break;
       }
    }
    if (has_bindless_io)