hw/virtio/vhost-vdpa: Use target-agnostic qemu_target_page_mask()

hw/virtio/vhost-vdpa: Use target-agnostic qemu_target_page_mask()

Similarly to commit e414ed2c47 ("virtio-iommu: Use
target-agnostic qemu_target_page_mask"), Replace the
target-specific TARGET_PAGE_SIZE and TARGET_PAGE_MASK
definitions by a call to the runtime qemu_target_page_size()
helper which is target agnostic.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20230710094931.84402-5-philmd@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>