[MMC] Use an IDR for host name indicies

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 113cc27..9a0893f 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -64,6 +64,7 @@
 struct mmc_host {
 	struct device		*dev;
 	struct class_device	class_dev;
+	int			index;
 	struct mmc_host_ops	*ops;
 	unsigned int		f_min;
 	unsigned int		f_max;