esp: add vmstate_esp version to embedded ESPState

esp: add vmstate_esp version to embedded ESPState

The QOM object representing ESPState is currently embedded within both the
SYSBUS_ESP and PCI_ESP devices with migration state handled by embedding
vmstate_esp within each device using VMSTATE_STRUCT.

Since the vmstate_esp fields are embedded directly within the migration
stream, the incoming vmstate_esp version_id is lost. The only version information
available is that from vmstate_sysbus_esp_scsi and vmstate_esp_pci_scsi, but
those versions represent their respective devices and not that of the underlying
ESPState.

Resolve this by adding a new version-dependent field in vmstate_sysbus_esp_scsi
and vmstate_esp_pci_scsi which stores the vmstate_esp version_id field within
ESPState to be used to allow migration from older QEMU versions.

Finally bump the vmstate_esp version to 5 to cover the upcoming ESPState changes
within this patch series.

Signed-off-by: Mark Cave-Ayland <[email protected]>
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Reviewed-by: Laurent Vivier <[email protected]>
Message-Id: <20210304221103[email protected]>