Bluetooth: hci_core: Fix leaking sent_cmd skb

[ Upstream commit dd3b1dc3

 ]

sent_cmd memory is not freed before freeing hci_dev causing it to leak
it contents.

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>