vfio: Split VFIO_GROUP_GET_STATUS into a function

This is the last sizable implementation in vfio_group_fops_unl_ioctl(),
move it to a function so vfio_group_fops_unl_ioctl() is emptied out.

Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/8-v2-0f9e632d54fb+d6-vfio_ioctl_split_jgg@nvidia.com


Signed-off-by: Alex Williamson <alex.williamson@redhat.com>