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/novena_defconfig b/configs/novena_defconfig
index 33cda1b..20c3aa1 100644
--- a/configs/novena_defconfig
+++ b/configs/novena_defconfig
@@ -48,6 +48,7 @@
 CONFIG_ENV_IS_IN_MMC=y
 CONFIG_SYS_REDUNDAND_ENVIRONMENT=y
 CONFIG_SYS_RELOC_GD_ENV_ADDR=y
+CONFIG_NETCONSOLE=y
 CONFIG_DM=y
 CONFIG_DWC_AHSATA=y
 CONFIG_FSL_USDHC=y