[PATCH v2 4/8] drm/xen-front: Implement Xen event channel handling

From: Oleksandr Andrushchenko Handle Xen event channels: - create for all configured connectors and publish corresponding ring references and event channels in Xen store, so backend can connect - implement event channels interrupt handlers - create

[PATCH v2 4/8] drm/xen-front: Implement Xen event channel handling

From: Oleksandr Andrushchenko Handle Xen event channels: - create for all configured connectors and publish corresponding ring references and event channels in Xen store, so backend can connect - implement event channels interrupt handlers - create and destroy event channels with