hpsa: do not ack controller events on controllers that do not support it

Acking controller events on controllers that do not support
it can cause such controllers to lock up.

Reviewed-by: Scott Teel <scott.teel@pmcs.com>
Signed-off-by: Joe Handzik <joseph.t.handzik@hp.com>
Signed-off-by: Don Brace <don.brace@pmcs.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>