vfio/ccw: Fix the missed unrealize() call in error path

vfio/ccw: Fix the missed unrealize() call in error path

When get name failed, we should call unrealize() so that
vfio_ccw_realize() is self contained.

Fixes: 909a6254eda ("vfio/ccw: Make vfio cdev pre-openable by passing a file handle")
Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-ID: <20240522170107.289532-7-clg@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>