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/smdkv310_defconfig b/configs/smdkv310_defconfig
index 2f2b4de..add0585 100644
--- a/configs/smdkv310_defconfig
+++ b/configs/smdkv310_defconfig
@@ -14,7 +14,7 @@
 CONFIG_IDENT_STRING=" for SMDKC210/V310"
 CONFIG_DISTRO_DEFAULTS=y
 CONFIG_SYS_LOAD_ADDR=0x43e00000
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="fatload mmc 0 40007000 uImage; bootm 40007000"
 # CONFIG_SPL_FRAMEWORK is not set
 CONFIG_SYS_PROMPT="SMDKV310 # "
 # CONFIG_CMD_XIMG is not set