iommu/vt-d: shift wrapping bug in prq_event_thread()

The "req->addr" variable is a bit field declared as "u64 addr:52;".
The "address" variable is a u64.  We need to cast "req->addr" to a u64
before the shift or the result is truncated to 52 bits.

Fixes: a222a7f0 ('iommu/vt-d: Implement page request handling')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>