ppc4xx: Fix problem with board_eth_init() vs cpu_eth_init() on AMCC boards

Some AMCC eval boards do have a board_eth_init() function calling
pci_eth_init(). These boards need to call cpu_eth_init() explicitly now
with the new eth_init rework.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/amcc/taihu/taihu.c b/board/amcc/taihu/taihu.c
index 5224378..669429b 100644
--- a/board/amcc/taihu/taihu.c
+++ b/board/amcc/taihu/taihu.c
@@ -195,5 +195,6 @@
 
 int board_eth_init(bd_t *bis)
 {
+	cpu_eth_init(bis);
 	return pci_eth_init(bis);
 }