Bluetooth: hci_sync: Check the correct flag before starting a scan

There's a very confusing mistake in the code starting a HCI inquiry: We're
calling hci_dev_test_flag() to test for HCI_INQUIRY, but hci_dev_test_flag()
checks hdev->dev_flags instead of hdev->flags. HCI_INQUIRY is a bit that's
set on hdev->flags, not on hdev->dev_flags though.

HCI_INQUIRY equals the integer 7, and in hdev->dev_flags, 7 means
HCI_BONDABLE, so we were actually checking for HCI_BONDABLE here.

The mistake is only present in the synchronous code for starting an inquiry,
not in the async one. Also devices are typically bondable while doing an
inquiry, so that might be the reason why nobody noticed it so far.

Fixes: abfeea47 ("Bluetooth: hci_sync: Convert MGMT_OP_START_DISCOVERY")
Signed-off-by: Jonas Dreßler <verdre@v0yd.nl>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>