Currently driver will attempt to process hotplug events concurrently based
on the FW interrupt.

Protect safw update function with a scan mutex.
Signed-off-by: NRaghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Signed-off-by: NMartin K. Petersen <martin.petersen@oracle.com>