Bug 944299 -Send CommandCompleteEvt with opcode when receving HCI_RESET

In Bluetooth core spec, HCI commands and Events, HCI_Reset:
"When the reset has been performed, a Command Complete event shall be
generated." bt-hci shall not reply Command Status event. We shall also
keep the last HCI command and put into Command Complete Event. Otherwise,
this invalid EventStatus event will be thrown away by bluedroid stack.

HCI Reset command returns a Command Complete event, not a Command Status
event.  We need to avoid resetting the stored last command code for the
response to be fully correct.

Signed-off-by: Andrzej Zaborowski <andrew.zaborowski@intel.com>