[IA64] hpsim, initialize chip for assigned irqs

Currently, when assign_irq_vector is called and the irq connected in
the simulator, the irq is not ready. request_irq will return ENOSYS
immediately. It is because the irq chip is unset.

Hence set the chip properly to irq_type_hp_sim. And make sure this is
done from both users of simulated interrupts.

Also we have to set handler here, otherwise we end up in
handle_bad_int resulting in spam in logs and no irqs handled. We use
handle_simple_irq as these are SW interrupts that need no ACK or
anything.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Tony Luck <tony.luck@intel.com>