dmaengine: dw-edma: Drop DT-region allocation

There is no point in allocating an additional memory for the data target
regions passed then to the client drivers. Just 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 End-point and
having it's CSRs accessible over a End-point' BAR. This case is only known
to be implemented as a part of the Synopsys PCIe EndPoint IP prototype
kit.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Tested-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Acked-By: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>