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_proc.c b/drivers/isdn/capi/kcapi_proc.c
index 59fd16a..71b0761 100644
--- a/drivers/isdn/capi/kcapi_proc.c
+++ b/drivers/isdn/capi/kcapi_proc.c
@@ -238,9 +238,9 @@
 // ---------------------------------------------------------------------------
 
 static void *capi_driver_start(struct seq_file *seq, loff_t *pos)
-	__acquires(&capi_drivers_list_lock)
+	__acquires(&capi_drivers_lock)
 {
-	read_lock(&capi_drivers_list_lock);
+	mutex_lock(&capi_drivers_lock);
 	return seq_list_start(&capi_drivers, *pos);
 }
 
@@ -250,9 +250,9 @@
 }
 
 static void capi_driver_stop(struct seq_file *seq, void *v)
-	__releases(&capi_drivers_list_lock)
+	__releases(&capi_drivers_lock)
 {
-	read_unlock(&capi_drivers_list_lock);
+	mutex_unlock(&capi_drivers_lock);
 }
 
 static int capi_driver_show(struct seq_file *seq, void *v)