drivers/isdn: Add module.h to ISDN files implicitly using it.

So that we don't get build failures once the implicit module.h
presence is terminated.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

drivers/isdn/hardware/mISDN/mISDNisar.c

@@ -29,6 +29,7 @@
 #include <linux/delay.h>
 #include <linux/vmalloc.h>
 #include <linux/mISDNhw.h>
+#include <linux/module.h>
 #include "isar.h"
 
 #define ISAR_REV	"2.1"