Update mx6sxsabresd board and config file
Note: Fastboot Android support is not added.
Signed-off-by: Peng Fan
CONFIG_SYS_EXTRA_OPTIONS="IMX_CONFIG=board/freescale/mx6sxsabresd/imximage.cfg,MX6SX,SYS_BOOT_QSPI" CONFIG_ARM=y CONFIG_TARGET_MX6SXSABRESD=y CONFIG_SYS_MALLOC_F=y CONFIG_SYS_MALLOC_F_LEN=0x400 CONFIG_DM=y CONFIG_DM_THERMAL=y