The SVA code is wired to assume that the SVA is programmed onto the
mm->pasid. The current core code always does this, so it is fine.

Add a check for clarity.
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v6-228e7adf25eb+4155-smmuv3_newapi_p2_jgg@nvidia.comSigned-off-by: Will Deacon <will@kernel.org>