spapr, xics, xive: Move irq claim and free from SpaprIrq to SpaprInterruptController

spapr, xics, xive: Move irq claim and free from SpaprIrq to SpaprInterruptController

These methods, like cpu_intc_create, really belong to the interrupt
controller, but need to be called on all possible intcs.

Like cpu_intc_create, therefore, make them methods on the intc and
always call it for all existing intcs.

Signed-off-by: David Gibson <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Reviewed-by: Cédric Le Goater <[email protected]>