AMD/IOMMU: drop tasklet handler forward declaration

do_amd_iommu_irq()'s forward declaration uses a parameter name different
from what the definition uses, thus vioating Misra C:2012 rule 8.3. We
can get away without such a forward declaration if instead we forward-
declare amd_iommu_irq_tasklet, putting its initialization past the
handler function's definition.

No functional change.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>

xen/drivers/passthrough/amd/iommu_init.c

@@ -26,8 +26,7 @@
 static int __initdata nr_amd_iommus;
 static bool __initdata pci_init;
 
-static void cf_check do_amd_iommu_irq(void *data);
-static DECLARE_SOFTIRQ_TASKLET(amd_iommu_irq_tasklet, do_amd_iommu_irq, NULL);
+static struct tasklet amd_iommu_irq_tasklet;
 
 unsigned int __read_mostly amd_iommu_acpi_info;
 unsigned int __read_mostly ivrs_bdf_entries;
@@ -715,6 +714,8 @@ static void cf_check do_amd_iommu_irq(void *unused)
     }
 }
 
+static DECLARE_SOFTIRQ_TASKLET(amd_iommu_irq_tasklet, do_amd_iommu_irq, NULL);
+
 static void cf_check iommu_interrupt_handler(
     int irq, void *dev_id, struct cpu_user_regs *regs)
 {