drm/xen-front: fix spelling mistake: "conector" -> "connector"

Trivial fix to spelling mistake in DRM_INFO message.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180515085433.8245-1-colin.king@canonical.com