dmaengine: mediatek-cqdma: fix wrong register usage in mtk_cqdma_start

This patch fixes wrong register usage in the mtk_cqdma_start. The
destination register should be MTK_CQDMA_DST2 instead.

Fixes: b1f01e48

 ("dmaengine: mediatek: Add MediaTek Command-Queue DMA controller for MT6765 SoC")
Signed-off-by: Shun-Chih Yu <shun-chih.yu@mediatek.com>
Cc: stable@vger.kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>