If including MX6SX in CONFIG_SYS_EXTRA_OPTIONS, CONFIG_ROM_UNIFIED_SECTIONS
will not effect.So move MX6SX to Kconfig entry from CONFIG_SYS_EXTRA_OPTIONS to
"select MX6SX" to boards using i.MX6 SoloX.
CONFIG_ARM=y
CONFIG_ARCH_MX6=y
CONFIG_TARGET_MX6SXSABRESD=y
CONFIG_SPL=y
CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/imx-common/spl_sd.cfg"
# CONFIG_CMD_IMLS is not set
# CONFIG_CMD_FLASH is not set
CONFIG_CMD_GPIO=y
# CONFIG_CMD_SETEXPR is not set
CONFIG_SPI_FLASH=y
