avr32: Use CONFIG_ATMEL_MCI to select the atmel_mci driver

After we move the atmel_mci driver into drivers/mmc, we can't select
it with CONFIG_MMC anymore. Introduce a new symbol specifically for
this driver so that there's no ambiguity.

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Acked-by: Jean-Chritophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/include/configs/atstk1004.h b/include/configs/atstk1004.h
index fc9585e..07add82 100644
--- a/include/configs/atstk1004.h
+++ b/include/configs/atstk1004.h
@@ -136,6 +136,7 @@
 #define CONFIG_PIO2			1
 #define CFG_HSDRAMC			1
 #define CONFIG_MMC			1
+#define CONFIG_ATMEL_MCI		1
 
 #define CFG_DCACHE_LINESZ		32
 #define CFG_ICACHE_LINESZ		32