ARM: atmel: at91sam9x5ek: enable spl support

Enable SPL support for at91sam9x5ek board. Now, it supports
boot up from NAND flash and SPI flash.

Signed-off-by: Bo Shen <voice.shen@atmel.com>
diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 25da926..bdf87f9 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -83,6 +83,7 @@
 config TARGET_AT91SAM9X5EK
 	bool "Atmel AT91SAM9X5-EK board"
 	select CPU_ARM926EJS
+	select SUPPORT_SPL
 
 config TARGET_SAMA5D3_XPLAINED
 	bool "SAMA5D3 Xplained board"