Bluetooth: hci_event: Fix Invalid wait context

This fixes the following trace caused by attempting to lock
cmd_sync_work_lock while holding the rcu_read_lock:

kworker/u3:2/212 is trying to lock:
ffff888002600910 (&hdev->cmd_sync_work_lock){+.+.}-{3:3}, at:
hci_cmd_sync_queue+0xad/0x140
other info that might help us debug this:
context-{4:4}
4 locks held by kworker/u3:2/212:
 #0: ffff8880028c6530 ((wq_completion)hci0#2){+.+.}-{0:0}, at:
 process_one_work+0x4dc/0x9a0
 ljalves#1: ffff888001aafde0 ((work_completion)(&hdev->rx_work)){+.+.}-{0:0},
 at: process_one_work+0x4dc/0x9a0
 ljalves#2: ffff888002600070 (&hdev->lock){+.+.}-{3:3}, at:
 hci_cc_le_set_cig_params+0x64/0x4f0
 ljalves#3: ffffffffa5994b00 (rcu_read_lock){....}-{1:2}, at:
 hci_cc_le_set_cig_params+0x2f9/0x4f0

Fixes: 26afbd8 ("Bluetooth: Add initial implementation of CIS connections")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

net/bluetooth/hci_event.c

@@ -3848,8 +3848,11 @@ static u8 hci_cc_le_set_cig_params(struct hci_dev *hdev, void *data,
 			   conn->handle, conn->link);
 
 		/* Create CIS if LE is already connected */
-		if (conn->link && conn->link->state == BT_CONNECTED)
+		if (conn->link && conn->link->state == BT_CONNECTED) {
+			rcu_read_unlock();
 			hci_le_create_cis(conn->link);
+			rcu_read_lock();
+		}
 
 		if (i == rp->num_handles)
 			break;