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/ls2080aqds_sdcard_defconfig b/configs/ls2080aqds_sdcard_defconfig
index 84a8f5d..6cde1d9 100644
--- a/configs/ls2080aqds_sdcard_defconfig
+++ b/configs/ls2080aqds_sdcard_defconfig
@@ -24,7 +24,7 @@
 CONFIG_BOOTDELAY=10
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 ramdisk_size=0x2000000 default_hugepagesz=2m hugepagesz=2m hugepages=256"
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="mmc read 0x80200000 0x6800 0x800; fsl_mc apply dpl 0x80200000 && mmc read $kernel_load $kernel_start $kernel_size && bootm $kernel_load"
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_USE_SECTOR=y
 CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR=0x8b0
 CONFIG_SPL_ENV_SUPPORT=y