Enable SPL support for at91sam9x5ek board. Now, it supports boot up from NAND flash and SPI flash.
Signed-off-by: Bo Shen
CONFIG_SPL=y CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9X5,SYS_USE_SPIFLASH" CONFIG_ARM=y CONFIG_ARCH_AT91=y CONFIG_TARGET_AT91SAM9X5EK=y