egl-wayland: Fix roundtrip eating wl_drm events in getServerProtocolsInfo

[amshafer]

This resolves another issue where the wl_drm events sent by the compositor are silently dropped by a roundtrip that happens before the wl_drm listener is registered. This change immediately registers wl_drm and triggers its roundtrip first. The dmabuf feedback can then proceed, potentially replacing the wl_drm name if a valid device was provided.