atm: Introduce vcc_process_recv_queue

This function moves the implementation found in the clip and br2684
modules to common code, correctly unlinks the skb from the queue
before pushing it and makes pppoatm use it.

Signed-off-by: Jorge Boncompte [DTI2] <jorge@dti2.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/atm/pppoatm.c b/net/atm/pppoatm.c
index db4a11c..df35d9a 100644
--- a/net/atm/pppoatm.c
+++ b/net/atm/pppoatm.c
@@ -303,6 +303,10 @@
 	atmvcc->push = pppoatm_push;
 	atmvcc->pop = pppoatm_pop;
 	__module_get(THIS_MODULE);
+
+	/* re-process everything received between connection setup and
+	   backend setup */
+	vcc_process_recv_queue(atmvcc);
 	return 0;
 }