dmaengine: stm32-dma3: defer channel registration to specify channel name

dmaengine: stm32-dma3: defer channel registration to specify channel name

On STM32 DMA3, channels can be reserved, so they are non available for
Linux. This non-availability creates a mismatch between dma_chan id and
DMA3 channel id.

Use dma_async_device_channel_register() to register the channels
after controller registration and change the default channel name, so that
it can match the name in the Reference Manual and ease requesting a channel
thanks to its name.

Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20240531150712.2503554-12-amelie.delaunay@foss.st.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>