During EEH PCI hotplug activity kernel unloads and loads the driver,
causing character device to be unregistered(aac_remove_one).When the
driver is loaded back using aac_probe_one the character device needs
to be registered again for the AIF management tools to work.

Fixed by adding code to register character device in aac_probe_one if
it is unregistered in aac_remove_one.
Signed-off-by: Raghava Aditya Renukunta <raghavaaditya.renukunta@pmcs.com>
Reviewed-by: Shane Seymour <shane.seymour@hpe.com>
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>