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/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c b/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c
index da69e75..da05589 100644
--- a/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c
+++ b/board/earthlcd/favr-32-ezkit/favr-32-ezkit.c
@@ -18,6 +18,7 @@
  * Place, Suite 330, Boston, MA 02111-1307 USA
  */
 #include <common.h>
+#include <netdev.h>
 
 #include <asm/io.h>
 #include <asm/sdram.h>
@@ -87,8 +88,6 @@
 }
 
 #if defined(CONFIG_MACB) && defined(CONFIG_CMD_NET)
-extern int macb_eth_initialize(int id, void *regs, unsigned int phy_addr);
-
 int board_eth_init(bd_t *bi)
 {
 	return macb_eth_initialize(0, (void *)MACB0_BASE, bi->bi_phy_id[0]);