Bluetooth: MGMT: Use hci_dev_test_and_{set,clear}_flag

This make use of hci_dev_test_and_{set,clear}_flag instead of doing 2
operations in a row.

Fixes: cbbdfa6f ("Bluetooth: Enable controller RPA resolution using Experimental feature")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>