drivers: net: vsc9953: Add LAG support

You can now configure LAG on VSC9953's ports using the command:
ethsw [port <port_no>] aggr {[help] | show | <lag_group_no>}

A port must belong to a single LAG. By default, a port
belongs to a LAG equal to the port's number.

For each frame, a hash will be calculated based on
Source/Destination MAC addresses, Source/Destination IP(v4/v6)
addresses, Source/Destination ports. This hash will be used to
select a single egress port from LAG. This also assures
that frames from the same flow will always have the
same egress port.

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@freescale.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
diff --git a/doc/README.t1040-l2switch b/doc/README.t1040-l2switch
index 4e0f418..6f03de2 100644
--- a/doc/README.t1040-l2switch
+++ b/doc/README.t1040-l2switch
@@ -31,6 +31,7 @@
 	- Port-based VLAN
 	- Private/Shared VLAN learning
 	- VLAN ingress filtering
+	- Port LAG
 
 Commands syntax
 ethsw [port <port_no>] { enable | disable | show } - enable/disable a port; show a port's configuration
@@ -45,6 +46,7 @@
 									  Tag's VID could be the frame's classified VID or the PVID of the port
 ethsw vlan fdb { [help] | show | shared | private } - make VLAN learning shared or private
 ethsw [port <port_no>] ingress filtering { [help] | show | enable | disable } - enable/disable VLAN ingress filtering on port
+ethsw [port <port_no>] aggr { [help] | show | <lag_group_no> } - get/set LAG group for a port
 
 => ethsw show
     Port   Status     Link    Speed   Duplex