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_pdu001_defconfig b/configs/am335x_pdu001_defconfig
index ffadc90..1c4c711 100644
--- a/configs/am335x_pdu001_defconfig
+++ b/configs/am335x_pdu001_defconfig
@@ -19,7 +19,7 @@
 CONFIG_AUTOBOOT_KEYED=y
 CONFIG_AUTOBOOT_PROMPT="Press SPACE to abort autoboot in %d seconds\n"
 CONFIG_AUTOBOOT_STOP_STR=" "
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="run eval_boot_device;part uuid mmc ${mmc_boot}:${root_fs_partition} root_fs_partuuid;setenv bootargs console=${console} vt.global_cursor_default=0 root=PARTUUID=${root_fs_partuuid} rootfstype=ext4 rootwait rootdelay=1;fatload mmc ${mmc_boot} ${fdtaddr} ${fdtfile};fatload mmc ${mmc_boot} ${loadaddr} ${bootfile};bootz ${loadaddr} - ${fdtaddr}"
 CONFIG_BOARD_LATE_INIT=y
 # CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR is not set
 CONFIG_SPL_I2C=y