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/sheevaplug_defconfig b/configs/sheevaplug_defconfig
index 40d50d6..34da356 100644
--- a/configs/sheevaplug_defconfig
+++ b/configs/sheevaplug_defconfig
@@ -37,6 +37,7 @@
 CONFIG_OF_CONTROL=y
 CONFIG_ENV_OVERWRITE=y
 CONFIG_ENV_IS_IN_NAND=y
+CONFIG_NETCONSOLE=y
 CONFIG_DM=y
 CONFIG_MVSATA_IDE=y
 CONFIG_MTD=y