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/am335x_shc_defconfig b/configs/am335x_shc_defconfig
index 4169d13..f2a6108 100644
--- a/configs/am335x_shc_defconfig
+++ b/configs/am335x_shc_defconfig
@@ -22,7 +22,7 @@
 CONFIG_AUTOBOOT_PROMPT="Enter 'shc' to enter prompt (times out) %d \nEnter 'noautoboot' to enter prompt without timeout\n"
 CONFIG_AUTOBOOT_DELAY_STR="shc"
 CONFIG_AUTOBOOT_STOP_STR="noautoboot"
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="if mmc dev 1; mmc rescan; then run emmc_setup; else echo ERROR: eMMC device not detected!; panic; fi; if run loaduimage; then run mmcboot; else echo ERROR Unable to load uImage from eMMC!; echo Performing Rollback!; setenv _active_ ${active_root}; setenv _inactive_ ${inactive_root}; setenv active_root ${_inactive_}; setenv inactive_root ${_active_}; saveenv; reset; fi; "
 CONFIG_DEFAULT_FDT_FILE="am335x-shc"
 CONFIG_SYS_CONSOLE_INFO_QUIET=y
 CONFIG_SPL_SYS_MALLOC_SIMPLE=y