Bluetooth: hci_uart: Fix uninitialized alignment value

Force alignment value to the default one (1 byte) if uninitialized.
This fixes hci_ll serdev driver (alignment = 0) and avoid any further
issues with upcoming drivers.

Signed-off-by: Loic Poulain <[e-mail]>
Signed-off-by: Johan Hedberg <[e-mail]>

drivers/bluetooth/hci_h4.c

···
 			    const struct h4_recv_pkt *pkts, int pkts_count)
 {
 	struct hci_uart *hu = hci_get_drvdata(hdev);
-	u8 alignment = hu->alignment;
+	u8 alignment = hu->alignment ? hu->alignment : 1;
 
 	while (count) {
 		int i, len;