st/va: use drm render node for wayland display type

With xwayland, vainfo use VA_DISPLAY_WAYLAND as default and it fails
and fails when specify display with  `vainfo --display wayland`.
In fact wayland support for libva uses drm path to connect device,
and should use drm pipe loader to create screen.

Signed-off-by: Leo Liu <leo.liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

src/gallium/state_trackers/va/context.c

@@ -114,7 +114,6 @@ VA_DRIVER_INIT_FUNC(VADriverContextP ctx)
 
    switch (ctx->display_type) {
    case VA_DISPLAY_ANDROID:
-   case VA_DISPLAY_WAYLAND:
       FREE(drv);
       return VA_STATUS_ERROR_UNIMPLEMENTED;
    case VA_DISPLAY_GLX:
@@ -127,6 +126,7 @@ VA_DRIVER_INIT_FUNC(VADriverContextP ctx)
       if (!drv->vscreen)
          goto error_screen;
       break;
+   case VA_DISPLAY_WAYLAND:
    case VA_DISPLAY_DRM:
    case VA_DISPLAY_DRM_RENDERNODES: {
       drm_info = (struct drm_state *) ctx->drm_state;