iommu/amd: Keep track of amd_iommu_irq_remap state

The amd_iommu_irq_remap variable is set to true in amd_iommu_prepare().
But if initialization fails it is not set to false. Fix that and
correctly keep track of whether irq remapping is enabled or not.

References: https://bugzilla.kernel.org/show_bug.cgi?id=212133
References: https://bugzilla.suse.com/show_bug.cgi?id=1183132
Fixes: b34f10c2dc59 ("iommu/amd: Stop irq_remapping_select() matching when remapping is disabled")
Cc: [e-mail] # v5.11
Signed-off-by: Joerg Roedel <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Acked-by: Huang Rui <[e-mail]>

drivers/iommu/amd/init.c

···
 	amd_iommu_irq_remap = true;
 
 	ret = iommu_go_to_state(IOMMU_ACPI_FINISHED);
-	if (ret)
+	if (ret) {
+		amd_iommu_irq_remap = false;
 		return ret;
+	}
+
 	return amd_iommu_irq_remap ? 0 : -ENODEV;
 }