dmaengine: stm32-dma3: introduce ddata2dev helper

dmaengine: stm32-dma3: introduce ddata2dev helper

The purpose of this helper is to 'standardize' device pointer retrieval,
similar to the chan2dev() helper.
ddata2dev() helper returns the device pointer from struct dma_device stored
in stm32_dma3_ddata structure.
Device pointer from struct dma_device has been initialized with &pdev->dev,
so the ddata2dev helper returns &pdev->dev.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://patch.msgid.link/20251121-dma3_improv-v2-4-76a207b13ea6@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>