mesa/fbo: don't check_end_texture_render on fb read change

Otherwise this resets is_rtt to false in st/mesa, and then
breaks fbo + texture view.

This change also aligns the code with the comment above:
    * Note that if the ReadBuffer has texture attachments we don't consider
    * that a render-to-texture case.

Acked-by: Gert Wollny <gert.wollny@collabora.com>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8387>

src/mesa/main/fbobject.c

@@ -3121,9 +3121,6 @@ _mesa_bind_framebuffers(struct gl_context *ctx,
    if (bindReadBuf) {
       FLUSH_VERTICES(ctx, _NEW_BUFFERS);
 
-      /* check if old readbuffer was render-to-texture */
-      check_end_texture_render(ctx, oldReadFb);
-
       _mesa_reference_framebuffer(&ctx->ReadBuffer, newReadFb);
    }