iommu/amd: Check return value of mmu_notifier_register()

Аdded a return value check for the function
mmu_notifier_register().

Return value of a function 'mmu_notifier_register'
called at iommu_v2.c:642 is not checked,
 but it is usually checked for this function

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Denis Arefev <arefev@swemel.ru>
Link: https://lore.kernel.org/r/20221118104252.122809-1-arefev@swemel.ru
[joro: Fix commit message ]
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: Denis Arefev

drivers/iommu/amd/iommu_v2.c

@@ -640,7 +640,9 @@ int amd_iommu_bind_pasid(struct pci_dev *pdev, u32 pasid,
 	if (pasid_state->mm == NULL)
 		goto out_free;
 
-	mmu_notifier_register(&pasid_state->mn, mm);
+	ret = mmu_notifier_register(&pasid_state->mn, mm);
+	if (ret)
+		goto out_free;
 
 	ret = set_pasid_state(dev_state, pasid_state, pasid);
 	if (ret)