dmaengine: dw-edma: Drop DT-region allocation

dmaengine: dw-edma: Drop DT-region allocation

There is no point in allocating additional memory for the data target
regions passed to the client drivers. Use the already available structures
defined in the dw_edma_chip instance.

Note: these regions are unused in normal circumstances since they are
specific to the case of eDMA being embedded into the DW PCIe Endpoint and
having its CSRs accessible via an Endpoint BAR. This case is only known to
be implemented as a part of the Synopsys PCIe Endpoint IP prototype kit.

Link: https://lore.kernel.org/r/20230113171409.30470-21-Sergey.Semin@baikalelectronics.ru
Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-by: Vinod Koul <vkoul@kernel.org>