new at91_emac network driver (NET_MULTI api)

* add's at91_emac (AT91RM9200) network driver (NET_MULTI api)
* enable driver with CONFIG_DRIVER_AT91EMAC
* generic PHY initialization
* modify AT91RM9200 boards to use NET_MULTI driver
* the drivers has been tested with LXT971 Phy and DM9161 Phy at
  MII and RMII interface

Signed-off-by: Jens Scharsig <js_at_ng@scharsoft.de>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/README b/README
index 263bb05..1158e24 100644
--- a/README
+++ b/README
@@ -822,6 +822,16 @@
 
 - NETWORK Support (other):
 
+		CONFIG_DRIVER_AT91EMAC
+		Support for AT91RM9200 EMAC.
+
+			CONFIG_RMII
+			Define this to use reduced MII inteface
+
+			CONFIG_DRIVER_AT91EMAC_QUIET
+			If this defined, the driver is quiet.
+			The driver doen't show link status messages.
+
 		CONFIG_DRIVER_LAN91C96
 		Support for SMSC's LAN91C96 chips.