mmc: refine DDR support

One flaw with DDR support is that MMC core does not inform the driver
which DDR mode it has selected.  This patch expands the ios->ddr flag
to do that.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index c4fb1c5..69ee1eb 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -54,7 +54,8 @@
 	unsigned char	ddr;			/* dual data rate used */
 
 #define MMC_SDR_MODE		0
-#define MMC_DDR_MODE		1
+#define MMC_1_2V_DDR_MODE	1
+#define MMC_1_8V_DDR_MODE	2
 };
 
 struct mmc_host_ops {