x86/hyperv: Refactor hv_msi_domain_free_irqs()

No point in looking up things over and over. Just look up the associated
irq data and work from there.

No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/20211206210224.429625690@linutronix.de