mmc: deprecate mmc bus topology

The classic MMC bus was defined as multi card bus
system, which is reflected in the design in the MMC
layer.

When SD showed up, the bus topology was abandoned
and a star topology (one card per host) was mandated.
MMC version 4 has followed this, officially deprecating
the bus topology.

As we do not have any known users of the bus
topology we can remove support for it. This will
simplify the code and rectify some incorrect
assumptions in the newer additions.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 92efe8e..6ea3c0e 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -138,14 +138,12 @@
 #define MMC_MODE_MMC		0
 #define MMC_MODE_SD		1
 
-	struct list_head	cards;		/* devices attached to this host */
+	struct mmc_card		*card;		/* device attached to this host */
 
 	wait_queue_head_t	wq;
 	spinlock_t		lock;		/* claimed lock */
 	unsigned int		claimed:1;	/* host exclusively claimed */
 
-	struct mmc_card		*card_selected;	/* the selected MMC card */
-
 	struct delayed_work	detect;
 #ifdef CONFIG_MMC_DEBUG
 	unsigned int		removed:1;	/* host is being removed */