iommu/amd: Use standard bitmap operation to set bitmap

#include <linux/pci.h>

#include <linux/acpi.h>

#include <linux/list.h>

#include <linux/bitmap.h>

#include <linux/slab.h>

#include <linux/syscore_ops.h>

#include <linux/interrupt.h>

	 * never allocate domain 0 because its used as the non-allocated and

	 * error value placeholder

	 */

	amd_iommu_pd_alloc_bitmap[0] = 1;

	__set_bit(0, amd_iommu_pd_alloc_bitmap);

	spin_lock_init(&amd_iommu_pd_lock);