iommu_sva_domain_alloc() is only called in iommu-sva.c, hence make it
static.

On the other hand, iommu_sva_domain_alloc() should not return NULL anymore
after commit <80af5a45> ("iommu: Add ops->domain_alloc_sva()"), the
removal of inline code avoids potential confusion.

Fixes: 80af5a45 ("iommu: Add ops->domain_alloc_sva()")
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20240528045458.81458-1-baolu.lu@linux.intel.comSigned-off-by: Joerg Roedel <jroedel@suse.de>