Bluetooth: hci_core: fix list_for_each_entry_rcu usage

[ Upstream commit 308a3a8c ]

Releasing + re-acquiring RCU lock inside list_for_each_entry_rcu() loop
body is not correct.

Fix by taking the update-side hdev->lock instead.

Fixes: c7eaf80b ("Bluetooth: Fix hci_link_tx_to RCU lock usage")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Reviewed-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>