Fix a typo from commit fa2f7b0b ("meson: Warn when TCI is
selected but TCG backend is available").

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210521103423.2780345-1-philmd@redhat.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>