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/ls1088aqds_qspi_defconfig b/configs/ls1088aqds_qspi_defconfig
index 37d42f3..7dfe1a6 100644
--- a/configs/ls1088aqds_qspi_defconfig
+++ b/configs/ls1088aqds_qspi_defconfig
@@ -23,7 +23,7 @@
 CONFIG_QSPI_BOOT=y
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 root=/dev/ram0 earlycon=uart8250,mmio,0x21c0500 ramdisk_size=0x3000000 default_hugepagesz=2m hugepagesz=2m hugepages=256"
-# CONFIG_USE_BOOTCOMMAND is not set
+CONFIG_BOOTCOMMAND="sf probe 0:0;sf read 0x80001000 0xd00000 0x100000; fsl_mc lazyapply dpl 0x80001000 && sf read $kernel_load $kernel_start $kernel_size && bootm $kernel_load"
 # CONFIG_DISPLAY_BOARDINFO is not set
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_CMD_GREPENV=y