Convert CONFIG_NETCONSOLE to Kconfig

This converts the following to Kconfig:
   CONFIG_NETCONSOLE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/db-88f6281-bp-nand_defconfig b/configs/db-88f6281-bp-nand_defconfig
index b690cd2..4fff326 100644
--- a/configs/db-88f6281-bp-nand_defconfig
+++ b/configs/db-88f6281-bp-nand_defconfig
@@ -39,6 +39,7 @@
 CONFIG_ENV_IS_IN_SPI_FLASH=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
 CONFIG_NET_RANDOM_ETHADDR=y
+CONFIG_NETCONSOLE=y
 CONFIG_DM=y
 CONFIG_MVSATA_IDE=y
 CONFIG_MTD=y