dmaengine: mv_xor_v2: explicitly freeup irq

dmaengine device should explicitly call devm_free_irq() when using
devm_request_irq().

The irq is still ON when devices remove is executed and irq should be
quiesced before remove is completed.

Signed-off-by: Hanna Hawa <hannah@marvell.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>