Instead of having all TYPE_CCW_DEVICE children set the bus type to
TYPE_VIRTUAL_CSS_BUS, do it once in the abstract parent.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Eric Farman <farman@linux.ibm.com>
Message-Id: <20210424145313.3287400-1-f4bug@amsat.org>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>