Bluetooth: hci_uart: Use const data pointer for received data

The TTY layer provides its data pointers as const, but the HCI UART
callbacks expect them as general data pointers. This is of course
wrong and instead of casting them, just fix the individual drivers
to actually take a const data pointer.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
diff --git a/drivers/bluetooth/hci_bcsp.c b/drivers/bluetooth/hci_bcsp.c
index 21cc45b..50ef2e6 100644
--- a/drivers/bluetooth/hci_bcsp.c
+++ b/drivers/bluetooth/hci_bcsp.c
@@ -554,10 +554,10 @@
 }
 
 /* Recv data */
-static int bcsp_recv(struct hci_uart *hu, void *data, int count)
+static int bcsp_recv(struct hci_uart *hu, const void *data, int count)
 {
 	struct bcsp_struct *bcsp = hu->priv;
-	unsigned char *ptr;
+	const unsigned char *ptr;
 
 	BT_DBG("hu %p count %d rx_state %d rx_count %ld", 
 		hu, count, bcsp->rx_state, bcsp->rx_count);