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/openrd_base_defconfig b/configs/openrd_base_defconfig
index 0e22f69..9e048d4 100644
--- a/configs/openrd_base_defconfig
+++ b/configs/openrd_base_defconfig
@@ -15,6 +15,8 @@
 CONFIG_SYS_LOAD_ADDR=0x800000
 CONFIG_SYS_EXTRA_OPTIONS="BOARD_IS_OPENRD_BASE"
 CONFIG_BOOTDELAY=3
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="${x_bootcmd_kernel}; setenv bootargs ${x_bootargs} ${x_bootargs_root}; ${x_bootcmd_usb}; bootm 0x6400000;"
 CONFIG_USE_PREBOOT=y
 CONFIG_LOGLEVEL=2
 # CONFIG_DISPLAY_BOARDINFO is not set