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: 2f5da678 ("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>