Introduce netdev.h header file and remove externs

This addresses all drivers whose initializers have already
been moved to board_eth_init()/cpu_eth_init().

Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
diff --git a/drivers/net/bfin_mac.c b/drivers/net/bfin_mac.c
index 3ee5d96..c5e74b8 100644
--- a/drivers/net/bfin_mac.c
+++ b/drivers/net/bfin_mac.c
@@ -9,6 +9,7 @@
 #include <common.h>
 #include <config.h>
 #include <net.h>
+#include <netdev.h>
 #include <command.h>
 #include <malloc.h>
 
diff --git a/drivers/net/greth.c b/drivers/net/greth.c
index 90c5338..79bc4d9 100644
--- a/drivers/net/greth.c
+++ b/drivers/net/greth.c
@@ -27,6 +27,7 @@
 #include <common.h>
 #include <command.h>
 #include <net.h>
+#include <netdev.h>
 #include <malloc.h>
 #include <asm/processor.h>
 #include <ambapp.h>
diff --git a/drivers/net/macb.c b/drivers/net/macb.c
index aa39284..08bebf7 100644
--- a/drivers/net/macb.c
+++ b/drivers/net/macb.c
@@ -40,6 +40,7 @@
  */
 
 #include <net.h>
+#include <netdev.h>
 #include <malloc.h>
 
 #include <linux/mii.h>
diff --git a/drivers/net/mcffec.c b/drivers/net/mcffec.c
index 50d6508..f93cf59 100644
--- a/drivers/net/mcffec.c
+++ b/drivers/net/mcffec.c
@@ -32,6 +32,7 @@
 
 #include <command.h>
 #include <net.h>
+#include <netdev.h>
 #include <miiphy.h>
 
 #undef	ET_DEBUG
diff --git a/drivers/net/sk98lin/uboot_drv.c b/drivers/net/sk98lin/uboot_drv.c
index 205e7d2..0199b33 100644
--- a/drivers/net/sk98lin/uboot_drv.c
+++ b/drivers/net/sk98lin/uboot_drv.c
@@ -24,6 +24,7 @@
  */
 
 #include <common.h>
+#include <netdev.h>
 
 #include "h/skdrv1st.h"
 #include "h/skdrv2nd.h"
diff --git a/drivers/net/uli526x.c b/drivers/net/uli526x.c
index d87638c..9ea5ac2 100644
--- a/drivers/net/uli526x.c
+++ b/drivers/net/uli526x.c
@@ -16,6 +16,7 @@
 #include <common.h>
 #include <malloc.h>
 #include <net.h>
+#include <netdev.h>
 #include <asm/io.h>
 #include <pci.h>
 #include <miiphy.h>