Accroding to the SMMUv3 spec, the SPAN field of Level1 Stream Table
Descriptor is 5 bits([4:0]).

Fixes: 9bde7f06(hw/arm/smmuv3: Implement translate callback)
Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
Message-id: 20201124023711.1184-1-jiangkunkun@huawei.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>