dm: allow autoloading of dm mod

Add devname:mapper/control and MAPPER_CTRL_MINOR module alias
to support dm-mod module autoloading.

Signed-off-by: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Peter Rajnoha <prajnoha@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/include/linux/miscdevice.h b/include/linux/miscdevice.h
index f6c9b7d..bafffc7 100644
--- a/include/linux/miscdevice.h
+++ b/include/linux/miscdevice.h
@@ -38,6 +38,7 @@
 #define KVM_MINOR		232
 #define BTRFS_MINOR		234
 #define AUTOFS_MINOR		235
+#define MAPPER_CTRL_MINOR	236
 #define MISC_DYNAMIC_MINOR	255
 
 struct device;