CAPI: Convert capi drivers rwlock into mutex

Turn the lock protecting registered capi drivers into a mutex and apply
it consistently.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/isdn/capi/kcapi.h b/drivers/isdn/capi/kcapi.h
index f62c53b..07c5850 100644
--- a/drivers/isdn/capi/kcapi.h
+++ b/drivers/isdn/capi/kcapi.h
@@ -30,7 +30,7 @@
 };
 
 extern struct list_head capi_drivers;
-extern rwlock_t capi_drivers_list_lock;
+extern struct mutex capi_drivers_lock;
 
 extern struct capi20_appl *capi_applications[CAPI_MAXAPPL];
 extern struct capi_ctr *capi_controller[CAPI_MAXCONTR];