vfio/iommufd: Implement [at|de]tach_hwpt handlers

vfio/iommufd: Implement [at|de]tach_hwpt handlers

Implement [at|de]tach_hwpt handlers in VFIO subsystem. vIOMMU
utilizes them to attach to or detach from hwpt on host side.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Link: https://lore.kernel.org/qemu-devel/20250604062115.4004200-4-zhenzhong.duan@intel.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>