PCI: dwc: Add EDMA_UNROLL capability flag

PCI: dwc: Add EDMA_UNROLL capability flag

Renesas R-Car Gen4 PCIe controllers have an unexpected register value in
the eDMA CTRL register.

So, add a new capability flag "EDMA_UNROLL" which would force the unrolled
eDMA mapping for the problematic device.

Suggested-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/linux-pci/20231018085631.1121289-7-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>