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/s5pc210_universal_defconfig b/configs/s5pc210_universal_defconfig
index 87001d3..a4d8e31 100644
--- a/configs/s5pc210_universal_defconfig
+++ b/configs/s5pc210_universal_defconfig
@@ -14,7 +14,7 @@
 CONFIG_SYS_LOAD_ADDR=0x44800000
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="Please use defined boot"
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="run mmcboot"
 CONFIG_SYS_CONSOLE_IS_IN_ENV=y
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_MISC_INIT_R=y