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/netspace_mini_v2_defconfig b/configs/netspace_mini_v2_defconfig
index 6d07e87..45c16d9 100644
--- a/configs/netspace_mini_v2_defconfig
+++ b/configs/netspace_mini_v2_defconfig
@@ -38,6 +38,7 @@
 CONFIG_USE_ENV_SPI_MAX_HZ=y
 CONFIG_ENV_SPI_MAX_HZ=20000000
 CONFIG_ENV_ADDR=0x70000
+CONFIG_NETCONSOLE=y
 CONFIG_DM=y
 CONFIG_SATA_MV=y
 CONFIG_BLK=y