mcb: Enable PCI bus mastering by default

In order to successfully perform DMA operations on PCI devices,
it is necessary to enble PCI bus mastering, so enable it by default.

Signed-off-by: Michael Moese <michael.moese@men.de>
Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>