Bluetooth: Remove unneeded hci_req_cmd_status function

This patch removes the hci_req_cmd_status function since it is not
used anymore. The HCI request framework now considers the HCI command
has complete once the Command Status or Command Complete Event is
received.

Signed-off-by: Andre Guedes <andre.guedes@openbossa.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>