Bluetooth: remove unneeded var initialization in btmrvl

There is no need to init ret to zero in  btmrvl_sdio_download_fw().
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

drivers/bluetooth/btmrvl_sdio.c

@@ -874,7 +874,7 @@ static int btmrvl_sdio_host_to_card(struct btmrvl_private *priv,
 
 static int btmrvl_sdio_download_fw(struct btmrvl_sdio_card *card)
 {
-	int ret = 0;
+	int ret;
 	u8 fws0;
 	int pollnum = MAX_POLL_TRIES;