panfrost: Release the ctx->pipe_framebuffer ref

ctx->pipe_framebuffer contains the last bound FB state, let's release
resources pointed by this FB state when the context is destroyed.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>

src/gallium/drivers/panfrost/pan_context.c

@@ -2448,6 +2448,7 @@ panfrost_destroy(struct pipe_context *pipe)
         if (panfrost->blitter_wallpaper)
                 util_blitter_destroy(panfrost->blitter_wallpaper);
 
+        util_unreference_framebuffer_state(&panfrost->pipe_framebuffer);
         u_upload_destroy(pipe->stream_uploader);
 
         ralloc_free(pipe);