Add compatibility with kernel v4.19

Signed-off-by: Fabien Parent <fparent@baylibre.com>
diff --git a/btmtk_main.c b/btmtk_main.c
index a75206f..4198425 100644
--- a/btmtk_main.c
+++ b/btmtk_main.c
@@ -146,7 +146,7 @@
 	struct btmtk_thread *thread = data;
 	struct btmtk_private *priv = thread->priv;
 	struct btmtk_adapter *adapter = NULL;
-	wait_queue_t wait;
+	wait_queue_entry_t wait;
 	struct sk_buff *skb;
 	int ret = 0;
 	int i = 0;