drivers: pci: pcie_dw_common: add upper-limit to iATU

The 4.6 spec added an upper 32bits to the ATU limit, and since this
driver is already assuming the unrolled feature added in the 4.8
specification this really should be set.

This is causing a bug with testing against the QEMU model as it
defaults the viewports to fully open and not setting this causes
the config viewport to become most of memory (obviously stopping
the emulated system working correctly)

Signed-off-by: Ben Dooks <ben.dooks@sifive.com>

pci: add common Designware PCIe functions

With the introduction of pcie_dw_rockchip, and need to support the DW PCIe in the
Amlogic AXG & G12 SoCs, most of the DW PCIe helpers would be duplicated.

This introduce a "common" DW PCIe helpers file with common code merged from the
dw_ti and dw_rockchip drivers and adapted to fit with the upcoming dw_meson.

The following changes will switch the dw_ti and dw_rockchip to use these helpers.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Green Wan <green.wan@sifive.com>
[bmeng: remove the blank line at EOF of drivers/pci/pcie_dw_common.c]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

pci: add common Designware PCIe functions

With the introduction of pcie_dw_rockchip, and need to support the DW PCIe in the
Amlogic AXG & G12 SoCs, most of the DW PCIe helpers would be duplicated.

This introduce a "common" DW PCIe helpers file with common code merged from the
dw_ti and dw_rockchip drivers and adapted to fit with the upcoming dw_meson.

The following changes will switch the dw_ti and dw_rockchip to use these helpers.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Green Wan <green.wan@sifive.com>
[bmeng: remove the blank line at EOF of drivers/pci/pcie_dw_common.c]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>