mmc: bcm2835: Fix dma_unmap_sg() nents value

The dma_unmap_sg() functions should be called with the same nents as the
dma_map_sg(), not the value the map function returned.

Fixes: 2f5da67 ("mmc: bcm2835: Properly handle dmaengine_prep_slave_sg")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250630093510.82871-2-fourier.thomas@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: Thomas-fourier

drivers/mmc/host/bcm2835.c

@@ -503,7 +503,8 @@ void bcm2835_prepare_dma(struct bcm2835_host *host, struct mmc_data *data)
 				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
 	if (!desc) {
-		dma_unmap_sg(dma_chan->device->dev, data->sg, sg_len, dir_data);
+		dma_unmap_sg(dma_chan->device->dev, data->sg, data->sg_len,
+			     dir_data);
 		return;
 	}