Bluetooth: hci_event: Fix using rcu_read_(un)lock while iterating

Bluetooth: hci_event: Fix using rcu_read_(un)lock while iterating

The usage of rcu_read_(un)lock while inside list_for_each_entry_rcu is
not safe since for the most part entries fetched this way shall be
treated as rcu_dereference:

	Note that the value returned by rcu_dereference() is valid
	only within the enclosing RCU read-side critical section [1]_.
	For example, the following is **not** legal::

		rcu_read_lock();
		p = rcu_dereference(head.next);
		rcu_read_unlock();
		x = p->address;	/* BUG!!! */
		rcu_read_lock();
		y = p->data;	/* BUG!!! */
		rcu_read_unlock();

Fixes: a0bfde167b50 ("Bluetooth: ISO: Add support for connecting multiple BISes")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>