pci: add Amlogic Meson Designware PCIe controller

Add support for the DW PCIe controller found in the Amlogic Meson AXG and
G12 (G12A, G12B, SM1) SoCs.
This uses the common DW PCIe helpers introducted previously.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index e3ca8b2..96d6182 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -50,5 +50,6 @@
 obj-$(CONFIG_PCIE_MEDIATEK) += pcie_mediatek.o
 obj-$(CONFIG_PCIE_ROCKCHIP) += pcie_rockchip.o
 obj-$(CONFIG_PCIE_DW_ROCKCHIP) += pcie_dw_rockchip.o
+obj-$(CONFIG_PCIE_DW_MESON) += pcie_dw_meson.o
 obj-$(CONFIG_PCI_BRCMSTB) += pcie_brcmstb.o
 obj-$(CONFIG_PCI_OCTEONTX) += pci_octeontx.o