MFC r313415:

[iwm] Implement apmg_wake_up_wa workaround properly for 7000 family.

• Add iwm_pcie_set_cmd_in_flight() and iwm_pcie_clear_cmd_in_flight() helper methods.

• Use ring->queued tracking in the command queue to set/clear the cmd_hold_nic_awake bit at the right points.