PCI: qcom-ep: Add eDMA support

Qualcomm PCIe Endpoint controllers have the in-built Embedded DMA (eDMA)
peripheral for offloading the data transfer between the PCIe bus and
memory.

Let's add support for it by enabling the eDMA IRQ in the driver. The
eDMA DMA Engine driver will handle the rest of the functionality.

Since the eDMA on Qualcomm platforms only uses a single IRQ for all
channels, use 1 for edma.nr_irqs.

[kwilczynski: commit log]
Link: https://lore.kernel.org/linux-pci/20230717065459.14138-4-manivannan.sadhasivam@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>