hw/virtio: move virtio-pci.h into shared include space

hw/virtio: move virtio-pci.h into shared include space

This allows other device classes that will be exposed via PCI to be
able to do so in the appropriate hw/ directory. I resisted the
temptation to re-order headers to be more aesthetically pleasing.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20200925125147.26943-4-alex.bennee@linaro.org>

Message-Id: <20220321153037.3622127-2-alex.bennee@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>