iommu/vt-d: Check return value of acpi_bus_get_device()
iommu/vt-d: Check return value of acpi_bus_get_device()

Checking adev == NULL is not sufficient as
acpi_bus_get_device() might not touch the value of this
parameter in an error case, so check the return value
directly.

Fixes: ed40356b5fcf1ce28e026ab39c5b2b6939068b50
Cc: David Woodhouse <97b3379caa91f4ee97e44013ae4dc6350540fa9d@infradead.org>
Signed-off-by: Joerg Roedel <61aff96566804ea1da8a65de5bcc892ce07caceb@suse.de>
Reviewed-by: Alex Williamson <7469de9b95ba379e2656fa9677689657c47a7690@redhat.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs