scsi: aacraid: Added support for hotplug

scsi: aacraid: Added support for hotplug

BugLink: http://bugs.launchpad.net/bugs/1668726
Added support for drive hotplug add and removal

Signed-off-by: Raghava Aditya Renukunta <RaghavaAditya.Renukunta@microsemi.com>
Signed-off-by: Dave Carroll <David.Carroll@microsemi.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
(cherry picked from linux-next commit 6223a39fe6fbbeef0877a56dc427a6351f22ef6c)
Signed-off-by: Seth Forshee <seth.forshee@canonical.com>