dma: Fix function names in documentation Ensure the function names match. Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com> Message-id: 20241012-dma-v2-1-6afddf5f3c8d@daynix.com Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>