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/dockstar_defconfig b/configs/dockstar_defconfig
index 44327cd..0b434f4 100644
--- a/configs/dockstar_defconfig
+++ b/configs/dockstar_defconfig
@@ -30,6 +30,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_NETCONSOLE=y
 # CONFIG_MMC is not set
 CONFIG_MTD=y
 CONFIG_MTD_RAW_NAND=y