svcrpc: never clear XPT_BUSY on dead xprt

Once an xprt has been deleted, there's no reason to allow it to be
enqueued--at worst, that might cause the xprt to be re-added to some
global list, resulting in later corruption.

Also, note this leaves us with no need for the reference-count
manipulation here.

Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

net/sunrpc/svc_xprt.c

@@ -936,10 +936,7 @@ void svc_close_xprt(struct svc_xprt *xprt)
 		/* someone else will have to effect the close */
 		return;
 
-	svc_xprt_get(xprt);
 	svc_delete_xprt(xprt);
-	clear_bit(XPT_BUSY, &xprt->xpt_flags);
-	svc_xprt_put(xprt);
 }
 EXPORT_SYMBOL_GPL(svc_close_xprt);