idr: export idr_get_next()

idr_get_next() was accidentally not exported when added.  It is about
to be used by mtdcore, which may be built as a module.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

lib/idr.c

@@ -621,7 +621,7 @@ void *idr_get_next(struct idr *idp, int *nextidp)
 	}
 	return NULL;
 }
-
+EXPORT_SYMBOL(idr_get_next);
 
 
 /**