iommu/riscv: Add RISCV_IOMMU_CAPABILITIES_NL

iommu/riscv: Add RISCV_IOMMU_CAPABILITIES_NL

Non-leaf invalidation allows the single invalidate command to also
clear the walk cache. If NL is available, set the NL bit if the
gather indicates tables have been changed. The stride is already
calculated properly.

Reviewed-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Andrew Jones <andrew.jones@oss.qualcomm.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>