Bluetooth: hci_conn: Fix using conn->le_{tx,rx}_phy as supported PHYs

Bluetooth: hci_conn: Fix using conn->le_{tx,rx}_phy as supported PHYs

conn->le_{tx,rx}_phy is not actually a bitfield as it set by
HCI_EV_LE_PHY_UPDATE_COMPLETE it is actually correspond to the current
PHY in use not what is supported by the controller, so this introduces
different fields (conn->le_{tx,rx}_def_phys) to track what PHYs are
supported by the connection.

Fixes: eab2404ba798 ("Bluetooth: Add BT_PHY socket option")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>