Convert CONFIG_USE_BOOTCOMMAND et al to Kconfig

This converts the following to Kconfig:
   CONFIG_USE_BOOTCOMMAND
   CONFIG_BOOTCOMMAND
   CONFIG_RAMBOOTCOMMAND
   CONFIG_NFSBOOTCOMMAND

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/netspace_lite_v2_defconfig b/configs/netspace_lite_v2_defconfig
index 15cc556..ff2ee67 100644
--- a/configs/netspace_lite_v2_defconfig
+++ b/configs/netspace_lite_v2_defconfig
@@ -17,6 +17,8 @@
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200"
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="dhcp && run netconsole; if run usbload || run diskload; then bootm; fi"
 CONFIG_USE_PREBOOT=y
 CONFIG_CONSOLE_MUX=y
 # CONFIG_DISPLAY_BOARDINFO is not set