Bluetooth: Fix __hci_req_sync

If hci_req_run returns error, we erroneously leave the current
process in TASK_INTERRUPTABLE state. If we leave the process in
TASK_INTERRUPTABLE and it is preempted, this process will never
be scheduled again.

This patch fixes this issue by moving the preparation for scheduling
(add to waitqueue and set process state) to just after the hci_req_run
call.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Acked-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>