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/T4240RDB_defconfig b/configs/T4240RDB_defconfig
index c66b152..d9c6fff 100644
--- a/configs/T4240RDB_defconfig
+++ b/configs/T4240RDB_defconfig
@@ -11,6 +11,8 @@
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_OF_STDOUT_VIA_ALIAS=y
 CONFIG_BOOTDELAY=10
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="setenv bootargs root=/dev/ram rw console=$consoledev,$baudrate $othbootargs;setenv ramdiskaddr 0x02000000;setenv fdtaddr 0x00c00000;setenv loadaddr 0x1000000;bootm $loadaddr $ramdiskaddr $fdtaddr"
 CONFIG_BOARD_EARLY_INIT_R=y
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_IMLS=y