ppc4xx: Remove unused feature from AR405 board

This patch fixes building for AR405 boards by remove an unused feature.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd.eu>
Signed-off-by: Stefan Roese <sr@denx.de>

include/configs/AR405.h

diff --git a/include/configs/AR405.h b/include/configs/AR405.h
index 73e34bd..52ead43 100644
--- a/include/configs/AR405.h
+++ b/include/configs/AR405.h
@@ -93,6 +93,7 @@
 #define CONFIG_CMD_IRQ
 #define CONFIG_CMD_ELF
 #define CONFIG_CMD_MII
+#undef CONFIG_CMD_NFS
 #define CONFIG_CMD_PING
 #define CONFIG_CMD_BSP