mesa: set a type for depth fallback texture

Otherwise we will later attempt to figure out format with type GL_NONE
which is not handled by _mesa_format_from_format_and_type.

Fixes: 0c6e56c391 ("mesa: (more) correctly handle incomplete depth textures")
Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/9012
Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Reviewed-by: Mike Blumenkrantz <michael.blumenkrantz@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/23013>

src/mesa/main/texobj.c

@@ -1071,7 +1071,7 @@ _mesa_get_fallback_texture(struct gl_context *ctx, gl_texture_index tex, bool is
       if (is_depth)
          texFormat = st_ChooseTextureFormat(ctx, target,
                                             GL_DEPTH_COMPONENT, GL_DEPTH_COMPONENT,
-                                            GL_NONE);
+                                            GL_UNSIGNED_INT);
       else
          texFormat = st_ChooseTextureFormat(ctx, target,
                                             GL_RGBA, GL_RGBA,