staging: unisys: visorbus: bus_destroy do not call bus_epilog

Have bus_destroy call chipset_bus_destroy directly instead of going
through bus_epilog.

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>