Bluetooth: Fix hci_inquiry

Since the HCI request framework was properly fixed to handle HCI
Inquiry commands, the hci_req_sync call, in hci_inquiry, will return
as soon as the HCI command completes (not the Inquiry procedure).
However, in inquiry ioctl implementation, we want to sleep the user
process until the inquiry procedure finishes.

This patch changes hci_inquiry so, in case the HCI Inquiry command
was executed successfully, it waits the HCI_INQUIRY flag to be cleared.
This way, the user process will sleep until the inquiry procedure
finishes.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>