Bluetooth: serdev: Constify serdev_device_ops

serdev_device_ops is not modified and can be const. Also, remove the
unneeded declaration of it.

Output from the file command before and after:

Before:
   text    data     bss     dec     hex filename
   7192    2408     192    9792    2640 drivers/bluetooth/hci_serdev.o

After:
   text    data     bss     dec     hex filename
   7256    2344     192    9792    2640 drivers/bluetooth/hci_serdev.o
Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/hci_serdev.c

@@ -21,8 +21,6 @@
 
 #include "hci_uart.h"
 
-static struct serdev_device_ops hci_serdev_client_ops;
-
 static inline void hci_uart_tx_complete(struct hci_uart *hu, int pkt_type)
 {
 	struct hci_dev *hdev = hu->hdev;
@@ -260,7 +258,7 @@ static int hci_uart_receive_buf(struct serdev_device *serdev, const u8 *data,
 	return count;
 }
 
-static struct serdev_device_ops hci_serdev_client_ops = {
+static const struct serdev_device_ops hci_serdev_client_ops = {
 	.receive_buf = hci_uart_receive_buf,
 	.write_wakeup = hci_uart_write_wakeup,
 };