mx6sxsabresd: Keep only one target

Currently there are two targets for the i.MX6SX SabreSD board:
mx6sxsabresd_defconfig and mx6sxsabresd_spl_defconfig.

This brings additional maintainance effort without a clear
advantage.

Keep only the mx6sxsabresd_defconfig one and remove
mx6sxsabresd_spl_defconfig to keep it simpler.

Also remove the SPL related code from the board file.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Peng Fan <peng.fan@nxp.com>

configs/mx6sxsabresd_spl_defconfig

@@ -1,69 +0,0 @@
-CONFIG_ARM=y
-CONFIG_ARCH_MX6=y
-CONFIG_SYS_TEXT_BASE=0x87800000
-CONFIG_SPL_GPIO_SUPPORT=y
-CONFIG_SPL_LIBCOMMON_SUPPORT=y
-CONFIG_SPL_LIBGENERIC_SUPPORT=y
-CONFIG_TARGET_MX6SXSABRESD=y
-CONFIG_ENV_SIZE=0x2000
-CONFIG_ENV_OFFSET=0xE0000
-CONFIG_DM_GPIO=y
-CONFIG_SPL_MMC_SUPPORT=y
-CONFIG_SPL_SERIAL_SUPPORT=y
-CONFIG_NR_DRAM_BANKS=1
-CONFIG_SPL=y
-CONFIG_SPL_LIBDISK_SUPPORT=y
-# CONFIG_CMD_BMODE is not set
-CONFIG_NXP_BOARD_REVISION=y
-CONFIG_SPL_TEXT_BASE=0x00908000
-CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=arch/arm/mach-imx/spl_sd.cfg"
-# CONFIG_CONSOLE_MUX is not set
-CONFIG_SYS_CONSOLE_IS_IN_ENV=y
-CONFIG_SUPPORT_RAW_INITRD=y
-CONFIG_BOUNCE_BUFFER=y
-CONFIG_SPL_FS_EXT4=y
-CONFIG_SPL_I2C_SUPPORT=y
-CONFIG_SPL_WATCHDOG_SUPPORT=y
-CONFIG_HUSH_PARSER=y
-CONFIG_CMD_BOOTZ=y
-CONFIG_CMD_GPIO=y
-CONFIG_CMD_I2C=y
-CONFIG_CMD_MMC=y
-CONFIG_CMD_PCI=y
-CONFIG_CMD_USB=y
-# CONFIG_CMD_SETEXPR is not set
-CONFIG_CMD_DHCP=y
-CONFIG_CMD_MII=y
-CONFIG_CMD_PING=y
-CONFIG_CMD_BMP=y
-CONFIG_CMD_CACHE=y
-CONFIG_CMD_TIME=y
-CONFIG_CMD_EXT2=y
-CONFIG_CMD_EXT4=y
-CONFIG_CMD_EXT4_WRITE=y
-CONFIG_CMD_FAT=y
-CONFIG_CMD_FS_GENERIC=y
-CONFIG_OF_CONTROL=y
-CONFIG_DEFAULT_DEVICE_TREE="imx6sx-sdb"
-CONFIG_SYS_RELOC_GD_ENV_ADDR=y
-CONFIG_ENV_VARS_UBOOT_RUNTIME_CONFIG=y
-CONFIG_DM_I2C=y
-CONFIG_DM_MMC=y
-CONFIG_FSL_USDHC=y
-CONFIG_PHYLIB=y
-CONFIG_MII=y
-CONFIG_PCI=y
-CONFIG_PINCTRL=y
-CONFIG_PINCTRL_IMX6=y
-CONFIG_DM_PMIC=y
-CONFIG_DM_PMIC_PFUZE100=y
-CONFIG_DM_REGULATOR=y
-CONFIG_DM_REGULATOR_PFUZE100=y
-CONFIG_DM_REGULATOR_FIXED=y
-CONFIG_DM_REGULATOR_GPIO=y
-CONFIG_USB=y
-CONFIG_DM_USB=y
-CONFIG_USB_STORAGE=y
-CONFIG_USB_HOST_ETHER=y
-CONFIG_USB_ETHER_ASIX=y
-CONFIG_VIDEO=y