dmaengine: mv_xor: Fix missing check after DMA map and missing unmap

The DMA map functions can fail and should be tested for errors.

In case of error, unmap the already mapped regions.

Fixes: 22843545 ("dma: mv_xor: Add support for DMA_INTERRUPT")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Link: https://lore.kernel.org/r/20250701123753.46935-2-fourier.thomas@gmail.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>