proper extern for mwave_s_mdd

This patch adds a proper extern for mwave_s_mdd in
drivers/char/mwave/mwavedd.h

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/char/mwave/mwavedd.h b/drivers/char/mwave/mwavedd.h
index 8eca61e..7e0d530 100644
--- a/drivers/char/mwave/mwavedd.h
+++ b/drivers/char/mwave/mwavedd.h
@@ -147,4 +147,6 @@
 
 } MWAVE_DEVICE_DATA, *pMWAVE_DEVICE_DATA;
 
+extern MWAVE_DEVICE_DATA mwave_s_mdd;
+
 #endif