Add back the ability to scan for hotplug changes while eh was in progress.

Schedule a rescan for a later time in the eh recovery code and wait for
eh to complete in the rescan worker.
Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>