Now that member can be made conditional, let's make SPICE chardev
conditional:

* spiceport, spicevmc

  Before and after the patch for !CONFIG_SPICE, the error is the
  same ('spiceport' is not a valid char driver name).

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20181213123724.4866-22-marcandre.lureau@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>