hpsa: correct handling of HBA device removal

Need to report HBA device removal faster than the
event handler polling interval.

Stop I/O to the removed disk and wait for all
I/O operations to flush before removing the device.

Reviewed-by: Scott Teel <scott.teel@microsemi.com>
Reviewed-by: Kevin Barnett <kevin.barnett@microsemi.com>
Signed-off-by: Don Brace <don.brace@microsemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>