mic: vop: Allow building on more systems

VOP_BUS does not actually depend on x86-64 or PCI or X86_DEV_DMA_OPS.

The dependency on X86_DEV_DMA_OPS has been unnecessary since commit
5657933d ("treewide: Move dma_ops from struct dev_archdata into
struct device").

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>