iommu/exynos: Fix suspend/resume with IDENTITY domain

Commit bcb81ac ("iommu: Get DT/ACPI parsing into the proper probe
path") changed the sequence of probing the SYSMMU controller devices and
calls to arm_iommu_attach_device(), what results in resuming SYSMMU
controller earlier, when it is still set to IDENTITY mapping. Such change
revealed the bug in IDENTITY handling in the exynos-iommu driver. When
SYSMMU controller is set to IDENTITY mapping, data->domain is NULL, so
adjust checks in suspend & resume callbacks to handle this case
correctly.

Fixes: b3d1496 ("iommu/exynos: Implement an IDENTITY domain")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20250401202731.2810474-1-m.szyprowski@samsung.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: mszyprow

drivers/iommu/exynos-iommu.c

@@ -832,7 +832,7 @@ static int __maybe_unused exynos_sysmmu_suspend(struct device *dev)
 		struct exynos_iommu_owner *owner = dev_iommu_priv_get(master);
 
 		mutex_lock(&owner->rpm_lock);
-		if (&data->domain->domain != &exynos_identity_domain) {
+		if (data->domain) {
 			dev_dbg(data->sysmmu, "saving state\n");
 			__sysmmu_disable(data);
 		}
@@ -850,7 +850,7 @@ static int __maybe_unused exynos_sysmmu_resume(struct device *dev)
 		struct exynos_iommu_owner *owner = dev_iommu_priv_get(master);
 
 		mutex_lock(&owner->rpm_lock);
-		if (&data->domain->domain != &exynos_identity_domain) {
+		if (data->domain) {
 			dev_dbg(data->sysmmu, "restoring state\n");
 			__sysmmu_enable(data);
 		}