iommu: Check return of __iommu_attach_device()

Currently iommu_create_device_direct_mappings() is called
without checking the return of __iommu_attach_device(). This
may result in failures in iommu driver if dev attach returns
error.

Fixes: ce574c27 ("iommu: Move iommu_group_create_direct_mappings() out of iommu_group_add_device()")
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20201119165846.34180-1-shameerali.kolothum.thodi@huawei.com


Signed-off-by: Will Deacon <will@kernel.org>