md: removing typedefs:  mdk_rdev_t -> struct md_rdev

The typedefs are just annoying. 'mdk' probably refers to 'md_k.h'
which used to be an include file that defined this thing.

Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid0.h b/drivers/md/raid0.h
index 91f8e87..9d877b8 100644
--- a/drivers/md/raid0.h
+++ b/drivers/md/raid0.h
@@ -11,7 +11,7 @@
 struct raid0_private_data
 {
 	struct strip_zone *strip_zone;
-	mdk_rdev_t **devlist; /* lists of rdevs, pointed to by strip_zone->dev */
+	struct md_rdev **devlist; /* lists of rdevs, pointed to by strip_zone->dev */
 	int nr_strip_zones;
 };