powerpc/iommu: Always release iommu_table in iommu_free_table()

At the moment iommu_free_table() only releases memory if
the table was initialized for the platform code use, i.e. it had
it_map initialized (which purpose is to track DMA memory space use).

With dynamic DMA windows, we will need to be able to release
iommu_table even if it was used for VFIO in which case it_map is NULL
so does the patch.
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/iommu.c

@@ -713,9 +713,11 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
 	unsigned long bitmap_sz;
 	unsigned int order;
 
-	if (!tbl || !tbl->it_map) {
-		printk(KERN_ERR "%s: expected TCE map for %s\n", __func__,
-				node_name);
+	if (!tbl)
+		return;
+
+	if (!tbl->it_map) {
+		kfree(tbl);
 		return;
 	}