Bluetooth: Add request cmd_complete and cmd_status functions

Bluetooth: Add request cmd_complete and cmd_status functions

This patch introduces functions to process the HCI request state when
receiving HCI Command Status or Command Complete events. Some HCI
commands, like Inquiry do not result in a Command complete event so
special handling is needed for them. Inquiry is a particularly important
one since it is the only forseeable "non-cmd_complete" command that will
make good use of the request functionality, and its completion is either
indicated by an Inquiry Complete event of a successful Command Complete
for HCI_Inquiry_Cancel.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>