ARM: atmel: add at91sam9g20ek_2mmc nand boot support

Add at91sam9g20_2mmc nand boot support. on this board, there is no
dataflash, so disable it

change one commet for at91sam9g20ek board

Signed-off-by: Bo Shen <voice.shen@atmel.com>
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/include/configs/at91sam9260ek.h b/include/configs/at91sam9260ek.h
index f921fac..02696b3 100644
--- a/include/configs/at91sam9260ek.h
+++ b/include/configs/at91sam9260ek.h
@@ -126,6 +126,7 @@
 #endif
 
 /* DataFlash */
+#ifndef CONFIG_AT91SAM9G20EK_2MMC
 #define CONFIG_ATMEL_DATAFLASH_SPI
 #define CONFIG_HAS_DATAFLASH		1
 #define CONFIG_SYS_SPI_WRITE_TOUT		(5*CONFIG_SYS_HZ)
@@ -133,6 +134,7 @@
 #define CONFIG_SYS_DATAFLASH_LOGIC_ADDR_CS0	0xC0000000	/* CS0 */
 #define CONFIG_SYS_DATAFLASH_LOGIC_ADDR_CS1	0xD0000000	/* CS1 */
 #define AT91_SPI_CLK			15000000
+#endif
 
 #ifdef CONFIG_AT91SAM9G20EK
 #define DATAFLASH_TCSS			(0x22 << 16)