* The controller firmware sends separate events for NVMe devices and
  PCIe switches similar to existing SAS events.

* NVMe device detection, addition and removal are reported by the
  firmware through PCIe Topology Change list events.

* The PCIe device state change events are sent when the firmware
  detects any abnormal conditions with a NVMe device or switch.

* The enumeration event are sent when the firmware starts PCIe device
  enumeration and stops.

* This patch has the code change to handle the events and add/remove
  NVMe devices in driver's inventory.
Signed-off-by: NChaitra P B <chaitra.basappa@broadcom.com>
Signed-off-by: NSuganath Prabu S <suganath-prabu.subramani@broadcom.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>