staging: unisys: visorbus: in my_device_destroy don't call device_epilog

The function my_device_destroy should call chipset_device_destroy
directly instead of calling device_epilog. Since this was the last
function to use device_epilog that function was removed as well.

Signed-off-by: David Kershner <david.kershner@unisys.com>
Reviewed-by: Tim Sell <Timothy.Sell@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>