Bluetooth: Check hci_req_run returning value in __hci_req_sync

Since hci_req_run will be returning more than one error code, we
should check its returning value in __hci_req_sync.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: HCI request error handling

When we are building a HCI request with more the one HCI command
and one of the hci_req_add calls fail, we should have some cleanup
routine so the HCI commands already queued on HCI request can be
deleted. Otherwise, we will face some memory leaks issues.

This patch implements the HCI request error handling which is the
following: If a hci_req_add fails, we save the error code in hci_
request. Once hci_req_run is called, we verify the error field. If
it is different from zero, we delete all HCI commands already queued
and return the error code.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Make hci_req_add returning void

Since no one checks the returning value of hci_req_add and HCI
request errors are now handled in hci_req_run, we can make hci_
req_add returning void.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Bluetooth: Check req->err in hci_req_add

If req->err is set, there is no point in queueing the HCI command
in HCI request command queue since it won't be sent anyway.

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