[MMC] Add multi block-write capability

Add a capability flag for drivers to set when they can perform multi-
block transfers to cards _and_ correctly report the number of bytes
transferred should an error occur.

The last point is very important - if a driver reports more bytes than
were actually accepted by the card and an error occurs, there is the
possibility for data loss.

Pierre Ossman provided the patch for wbsd and sdhci.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
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 ba095ae..b282ec9 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -85,6 +85,7 @@
 	unsigned long		caps;		/* Host capabilities */
 
 #define MMC_CAP_4_BIT_DATA	(1 << 0)	/* Can the host do 4 bit transfers */
+#define MMC_CAP_MULTIWRITE	(1 << 1)	/* Can accurately report bytes sent to card on error */
 
 	/* host specific block data */
 	unsigned int		max_seg_size;	/* see blk_queue_max_segment_size */