AM3517:Build FIX: undef CONFIG_CMD_NFS support

Without CONFIG_CMD_NET support CONFIG_CMD_NFS leads
to linking error, so disable CONFIG_CMD_NFS option.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>

include/configs/am3517_evm.h

@@ -163,6 +163,7 @@
 #define CONFIG_DRIVER_OMAP34XX_I2C	1
 
 #undef CONFIG_CMD_NET
+#undef CONFIG_CMD_NFS
 /*
  * Board NAND Info.
  */