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/tqma6q_mba6_spi_defconfig b/configs/tqma6q_mba6_spi_defconfig
index c7faa10..8d96c60 100644
--- a/configs/tqma6q_mba6_spi_defconfig
+++ b/configs/tqma6q_mba6_spi_defconfig
@@ -15,6 +15,8 @@
 CONFIG_SUPPORT_RAW_INITRD=y
 CONFIG_OF_BOARD_SETUP=y
 CONFIG_BOOTDELAY=3
+CONFIG_USE_BOOTCOMMAND=y
+CONFIG_BOOTCOMMAND="sf probe; run mmcboot; run netboot; run panicboot"
 CONFIG_DEFAULT_FDT_FILE="imx6q-mba6x.dtb"
 CONFIG_HUSH_PARSER=y
 CONFIG_CMD_BOOTZ=y