x86/msi: Consolidate MSI allocation

Convert the interrupt remap drivers to retrieve the pci device from the msi
descriptor and use info::hwirq.

This is the first step to prepare x86 for using the generic MSI domain ops.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20200826112332.466405395@linutronix.de

drivers/pci/controller/pci-hyperv.c

@@ -1534,7 +1534,7 @@ static struct irq_chip hv_msi_irq_chip = {
 static irq_hw_number_t hv_msi_domain_ops_get_hwirq(struct msi_domain_info *info,
 						   msi_alloc_info_t *arg)
 {
-	return arg->msi_hwirq;
+	return arg->hwirq;
 }
 
 static struct msi_domain_ops hv_msi_ops = {