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/ls1046aqds_sdcard_qspi_defconfig b/configs/ls1046aqds_sdcard_qspi_defconfig
index 10b3b66..cd7d180 100644
--- a/configs/ls1046aqds_sdcard_qspi_defconfig
+++ b/configs/ls1046aqds_sdcard_qspi_defconfig
@@ -34,7 +34,7 @@
 CONFIG_BOOTDELAY=10
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 mtdparts=1550000.spi-0:2m(uboot),14m(free)"
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="run distro_bootcmd; run sd_bootcmd; env exists secureboot && esbc_halt;;"
 CONFIG_MISC_INIT_R=y
 CONFIG_SPL_FSL_PBL=y
 CONFIG_SPL_BOARD_INIT=y