iommu/vt-d: Remove unused variable

commit 509fca89 upstream.

Unused after commit 71684406 ("iommu/vt-d: Detach domain *only*
from attached iommus").  Reported by 0-day builder.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/iommu/intel-iommu.c

@@ -1759,7 +1759,6 @@ static int domain_init(struct dmar_domain *domain, int guest_width)
 
 static void domain_exit(struct dmar_domain *domain)
 {
-	struct dmar_drhd_unit *drhd;
 	struct page *freelist = NULL;
 	int i;