dmaengine: dw-edma: Fix programming the source & dest addresses for ep

When eDMA is controlled by the Endpoint (EP), the current logic incorrectly
programs the source and destination addresses for read and write. Since the
Root complex and Endpoint uses the opposite channels for read/write, fix the
issue by finding out the read operation first and program the eDMA accordingly.

Cc: stable@vger.kernel.org
Fixes: bd96f1b2 ("dmaengine: dw-edma: support local dma device transfer semantics")
Fixes: e63d79d1 ("dmaengine: Add Synopsys eDMA IP core driver")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>