There exists a gap at the end of mdev_device_create() where the device
is visible to userspace, but we're not yet ready to handle removal, as
triggered through the 'remove' attribute.  We handle this properly in
mdev_device_remove() with an -EAGAIN return, but we can marginally
reduce this gap by adding this attribute as a final step of our sysfs
setup.
Reviewed-by: NKirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: NCornelia Huck <cohuck@redhat.com>
Acked-by: NHalil Pasic <pasic@linux.ibm.com>
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>