mesa: don't call _mesa_set_varying_vp_inputs in set_vertex_processing_mode

It's redundant because it's always called in _mesa_update_draw_vao.

Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19953>

src/mesa/main/state.c

@@ -684,12 +684,6 @@ set_vertex_processing_mode(struct gl_context *ctx, gl_vertex_processing_mode m)
    default:
       assert(0);
    }
-
-   /* Since we only track the varying inputs while being in fixed function
-    * vertex processing mode, we may need to update fixed-func shaders
-    * for zero-stride vertex attribs.
-    */
-   _mesa_set_varying_vp_inputs(ctx, ctx->Array._DrawVAOEnabledAttribs);
 }