usb: musb: fix debug global variable name

In order to avoid namespace conflicts, add a prefix
to our kernel-wise symbol.

Signed-off-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/musb/musb_debug.h b/drivers/usb/musb/musb_debug.h
index 4d27944..9fc1db4 100644
--- a/drivers/usb/musb/musb_debug.h
+++ b/drivers/usb/musb/musb_debug.h
@@ -48,11 +48,11 @@
 				__func__, __LINE__ , ## args); \
 	} } while (0)
 
-extern unsigned debug;
+extern unsigned musb_debug;
 
 static inline int _dbg_level(unsigned l)
 {
-	return debug >= l;
+	return musb_debug >= l;
 }
 
 #define DBG(level, fmt, args...) xprintk(level, KERN_DEBUG, fmt, ## args)