mcb: Add a dma_device to mcb_device

When performing DMA operations on a MCB device, the device needed
for using the DMA API is "mcb_device->bus_carrier".
This is rather lengthy, so a shortcut is introduced to struct mcb_device
in order to ensure the MCB device driver uses the correct device for DMA
operations.

Signed-off-by: Michael Moese <michael.moese@men.de>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/mcb.h b/include/linux/mcb.h
index ee5200d..4097ac9 100644
--- a/include/linux/mcb.h
+++ b/include/linux/mcb.h
@@ -76,6 +76,7 @@
 	int rev;
 	struct resource irq;
 	struct resource mem;
+	struct device *dma_dev;
 };
 
 static inline struct mcb_device *to_mcb_device(struct device *dev)