PCI: dwc: Refactor dw_pcie_edma_find_chip() API

In order to add support for Hyper DMA (HDMA), refactor the existing
dw_pcie_edma_find_chip() API by moving the common code to separate
functions.

No functional change.

Suggested-by: Serge Semin <fancer.lancer@gmail.com>
Link: https://lore.kernel.org/linux-pci/20240318-dw-hdma-v5-1-f04c5cdde760@linaro.org


Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Frank Li <frank.li@nxp.com>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>