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/dreamplug_defconfig b/configs/dreamplug_defconfig
index ea8c252..2c27726 100644
--- a/configs/dreamplug_defconfig
+++ b/configs/dreamplug_defconfig
@@ -32,6 +32,7 @@
 CONFIG_USE_ENV_SPI_MAX_HZ=y
 CONFIG_ENV_SPI_MAX_HZ=50000000
 CONFIG_ENV_ADDR=0x100000
+CONFIG_NETCONSOLE=y
 CONFIG_DM=y
 CONFIG_MVSATA_IDE=y
 CONFIG_BLK=y