dmaengine: tegra-apb: Improve error message about DMA underflow

Technically it is possible that DMA could be misconfigured in a way that
cyclic DMA transfer is processed slower than it takes to complete the
cycle and in this case the DMA is getting aborted with a not very
informative message about the problem, let's improve it.
Suggested-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Link: https://lore.kernel.org/r/20200209163356.6439-20-digetx@gmail.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/tegra20-apb-dma.c

@@ -566,7 +566,7 @@ static bool handle_continuous_head_request(struct tegra_dma_channel *tdc,
 	if (!hsgreq->configured) {
 		tegra_dma_stop(tdc);
 		pm_runtime_put(tdc->tdma->dev);
-		dev_err(tdc2dev(tdc), "Error in DMA transfer, aborting DMA\n");
+		dev_err(tdc2dev(tdc), "DMA transfer underflow, aborting DMA\n");
 		tegra_dma_abort_all(tdc);
 		return false;
 	}