Bluetooth: mediatek: Fix memory leak

In case memory resources for *fw* were allocated, release them before
return.

Addresses-Coverity-ID: 1472611 ("Resource leak")
Fixes: 7237c4c9ec92 ("Bluetooth: mediatek: Add protocol support for MediaTek serial devices")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Acked-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/btmtkuart.c

@@ -144,8 +144,10 @@ static int mtk_setup_fw(struct hci_dev *hdev)
 	fw_size = fw->size;
 
 	/* The size of patch header is 30 bytes, should be skip */
-	if (fw_size < 30)
-		return -EINVAL;
+	if (fw_size < 30) {
+		err = -EINVAL;
+		goto free_fw;
+	}
 
 	fw_size -= 30;
 	fw_ptr += 30;
@@ -172,8 +174,8 @@ static int mtk_setup_fw(struct hci_dev *hdev)
 		fw_ptr += dlen;
 	}
 
+free_fw:
 	release_firmware(fw);
-
 	return err;
 }