banned.h: fix vsprintf warning

Previously sprintf was the argument to the BANNED macro, where vsprintf
is expected.

Signed-off-by: Andrey Portnoy <aportnoy@ucsd.edu>

Author: andportnoy

banned.h

@@ -26,7 +26,7 @@
 #define vsprintf(...) BANNED(vsprintf)
 #else
 #define sprintf(buf,fmt,arg) BANNED(sprintf)
-#define vsprintf(buf,fmt,arg) BANNED(sprintf)
+#define vsprintf(buf,fmt,arg) BANNED(vsprintf)
 #endif
 
 #endif /* BANNED_H */