[bug report] iommu/arm-smmu: Make use of the iommu_register interface

[Dan Carpenter <dan.carpenter-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>]

Hello Joerg Roedel,

This is a semi-automatic email about new static checker warnings.

The patch 9648cbc9625b: "iommu/arm-smmu: Make use of the 
iommu_register interface" from Feb 1, 2017, leads to the following 
Smatch complaint:

    ./drivers/iommu/arm-smmu-v3.c:1957 arm_smmu_remove_device()
    warn: variable dereferenced before check 'master' (see line 1956)

./drivers/iommu/arm-smmu-v3.c
  1955		master = fwspec->iommu_priv;
  1956		smmu = master->smmu;
                       ^^^^^^^^^^^^
Pach adds unchecked dereference

  1957		if (master && master->ste.assigned)
                    ^^^^^^
The old code assumes "master" can be NULL.

  1958			arm_smmu_detach_dev(dev);
  1959		iommu_group_remove_device(dev);

regards,
dan carpenter