Merge changes from topic "mailbox-fixes" into integration

* changes:
  intel: Fix SMC SIP service
  intel: Introduce mailbox response length handling
  intel: Fix mailbox config return status
  intel: Mailbox driver logic fixes
  plat: intel: Fix FPGA manager on reconfiguration
  plat: intel: Fix mailbox send_cmd issue
  intel: Modify mailbox's get_config_status