iommu/intel: add missing free_domain_mem

Add missing free_domain_mem on failure path after alloc_domain.

A simplified version of the semantic match that finds this
problem is as follows: (http://coccinelle.lip6.fr/)

// <smpl>
@km exists@
local idexpression e;
expression e1,e2,e3;
type T,T1;
identifier f;
@@

* e = alloc_domain(...)
... when any
    when != e = e1
    when != e1 = (T)e
    when != e1(...,(T)e,...)
    when != &e->f
if(...) { ... when != e2(...,(T1)e,...)
                 when != e3 = e
                 when forall
(
             return <+...e...+>;
|
*             return ...;
) }
// </smpl>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>

drivers/iommu/intel-iommu.c

@@ -2008,6 +2008,7 @@ static struct dmar_domain *get_domain_for_dev(struct pci_dev *pdev, int gaw)
 	if (!drhd) {
 		printk(KERN_ERR "IOMMU: can't find DMAR for device %s\n",
 			pci_name(pdev));
+		free_domain_mem(domain);
 		return NULL;
 	}
 	iommu = drhd->iommu;